1
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Elbaz Y, Caspary Toroker M. From density functional theory to machine learning predictive models for electrical properties of spinel oxides. Sci Rep 2024; 14:12150. [PMID: 38802595 DOI: 10.1038/s41598-024-62788-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 05/17/2024] [Indexed: 05/29/2024] Open
Abstract
This work focuses on predicting and characterizing the electronic conductivity of spinel oxides, which are promising materials for energy storage devices and for the oxygen evolution and oxygen reduction reactions due to their attractive properties and abundance of transition metals that can act as active sites for catalysis. To this end, a new database was developed from first principles, including band structure and conductivity properties of spinel oxides, and machine learning algorithms were trained on this database to predict electronic conductivity and band gaps based solely on the compositions. The models developed in this study are scaled from the quantum level up to a continuum conductivity model. The relatively small database used in this study allowed for accurate predictions of band gap and conductivity. By altering the composition of spinel oxides, the model was able to predict high conductivity for spinels with high nickel content and to match experimental trends for manganese cobalt spinels. The ability to predict material properties is especially important in energy conversion devices such as batteries and supercapacitors where redox reactions take place.
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Affiliation(s)
- Yuval Elbaz
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, 3600003, Haifa, Israel
| | - Maytal Caspary Toroker
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, 3600003, Haifa, Israel.
- The Nancy and Stephen Grand Technion Energy Program, Technion - Israel Institute of Technology, 3600003, Haifa, Israel.
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2
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Bâldea I. Comment on "A single level tunneling model for molecular junctions: evaluating the simulation methods" by E. M. Opodi, X. Song, X. Yu and W. Hu, Phys. Chem. Chem. Phys., 2022, 24, 11958". Phys Chem Chem Phys 2024; 26:7230-7235. [PMID: 38329445 DOI: 10.1039/d2cp05110a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
The present Comment demonstrates important flaws of the paper Opodi et al. Phys. Chem. Chem. Phys., 2022, 24, 11958 Their crown result ("applicability map") aims at indicating parameter ranges wherein two approximate methods (called method 2 and 3) apply. My calculations reveal that the applicability map is a factual error. Deviations of I2 from the exact current I1 do not exceed 3% for model parameters where Opodi et al. claimed that method 2 is inapplicable. As for method 3, the parameter range of the applicability map is beyond its scope, as stated in papers cited by Opodi et al. themselves.
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Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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3
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Bâldea I. Can tunneling current in molecular junctions be so strongly temperature dependent to challenge a hopping mechanism? Analytical formulas answer this question and provide important insight into large area junctions. Phys Chem Chem Phys 2024; 26:6540-6556. [PMID: 38328878 DOI: 10.1039/d3cp05046g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Analytical equations like Richardson-Dushman's or Shockley's provided a general, if simplified conceptual background, which was widely accepted in conventional electronics and made a fundamental contribution to advances in the field. In the attempt to develop a (highly desirable, but so far missing) counterpart for molecular electronics, in this work, we deduce a general analytical formula for the tunneling current through molecular junctions mediated by a single level that is valid for any bias voltage and temperature. Starting from this expression, which is exact and obviates cumbersome numerical integration, in the low and high temperature limits we also provide analytical formulas expressing the current in terms of elementary functions. They are accurate for broad model parameter ranges relevant for real molecular junctions. Within this theoretical framework we show that: (i) by varying the temperature, the tunneling current can vary by several orders of magnitude, thus debunking the myth that a strong temperature dependence of the current is evidence for a hopping mechanism, (ii) real molecular junctions can undergo a gradual (Sommerfeld-Arrhenius) transition from a weakly temperature dependent to a strongly ("exponential") temperature dependent current that can be tuned by the applied bias, and (iii) important insight into large area molecular junctions with eutectic gallium indium alloy (EGaIn) top electrodes can be gained. E.g., merely based on transport data, we estimate that the current carrying molecules represent only a fraction of f ≈ 4 × 10-4 out of the total number of molecules in a large area Au-S-(CH2)13-CH3/EGaIn junction.
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Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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4
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Bâldea I. Can room-temperature data for tunneling molecular junctions be analyzed within a theoretical framework assuming zero temperature? Phys Chem Chem Phys 2023. [PMID: 37439691 DOI: 10.1039/d3cp00740e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Routinely, experiments on tunneling molecular junctions report values of conductances (GRT) and currents (IRT) measured at room temperature. On the other hand, theoretical approaches based on simplified models provide analytic formulas for the conductance (G0K) and current (I0K) valid at zero temperature. Therefore, interrogating the applicability of the theoretical results deduced in the zero-temperature limit to real experimental situations at room temperature (i.e., GRT ≈ G0K and IRT ≈ I0K) is a relevant aspect. Quantifying the pertaining temperature impact on the transport properties computed within the ubiquitous single-level model with Lorentzian transmission is the specific aim of the present work. Comprehensive results are presented for broad ranges of the relevant parameters (level's energy offset ε0 and width Γa, and applied bias V) that safely cover values characterizing currently fabricated junctions. They demonstrate that the strongest thermal effects occur at biases below resonance (2|ε0| - δε0 - 0.3 ≲ |eV| - 0.3 ≲ 2|ε0|). At fixed V, they affect an ε0-range whose largest width δε0 is about nine times larger than the thermal energy (δε0 ≈ 3πkBT) at Γa → 0. The numerous figures included aim to convey a quick overview on the applicability of the zero-temperature limit to a specific real junction. In quantitative terms, the conditions of applicability are expressed as mathematical inequalities involving elementary functions. They constitute the basis of a proposed interactive data-fitting procedure, which aims to guide experimentalists interested in data processing in a specific case.
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Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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5
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Li H, Li Z. Quasi-periodic scattering of topological edge states induced by the vacancies in chloridized gallium bismuthide nanoribbons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:255302. [PMID: 36990103 DOI: 10.1088/1361-648x/acc8ae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 03/29/2023] [Indexed: 06/19/2023]
Abstract
The chloridized gallium bismuthide was predicted to be a two-dimensional topological insulator with large topological band gap. It may be beneficial for achieving the quantum spin Hall effect and its related applications at high temperatures. To better understand the quantum transport in topological nanoribbons, we investigated the effect of vacancy on the quantum transport of topological edge states in the armchair chloridized gallium bismuthide nanoribbons by combining density functional theory and nonequilibrium Green's function. The results suggest the vacancies at center are more likely to cause the scattering of topological edge states. The average scattering is insensitive to the enlargement of vacancy along the transport direction. More interestingly, the obvious scattering of topological edge states can only be found at some special energies, and these special energies are distributed quasi-periodically. The quasi-periodic scattering may be used as a kind of fingerprint of vacancies. Our studies may be helpful for the application of topological nanoribbons.
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Affiliation(s)
- Hangyu Li
- College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Zhongyao Li
- College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
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6
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Wu CW, Pan H, Zeng YJ, Zhou WX, Chen KQ, Zhang G. Nano-phononic metamaterials enable an anomalous enhancement in the interfacial thermal conductance of the GaN/AlN heterojunction. NANOSCALE 2023; 15:6732-6737. [PMID: 36939614 DOI: 10.1039/d2nr05954a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Improving the interfacial thermal conductance (ITC) is very important for heat dissipation in microelectronic and optoelectronic devices. In this work, taking GaN-AlN contact as an example, we demonstrated a new mechanism to enhance the interfacial thermal conductance using nano-phononic metamaterials. First, how a superlattice affects the ITC is investigated, and it is found that with decreasing superlattice periodic length, the ITC first decreases and then increases, because of the coherent phonon interference effect. However, although constructing a superlattice is effective for tuning the ITC, it cannot enhance the ITC. We suggest that the ITC can be enhanced by 9% through constructing an interfacial nano phononic metamaterial, which is contributed by the additional phonon transport channels for high-frequency phonons with a wide incidence-angle range. These results not only establish a deep understanding of the fundamental physics of the interfacial thermal conductance, but also provide a robust and scalable mechanism, which provides a degree of freedom for efficient thermal management.
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Affiliation(s)
- Cheng-Wei Wu
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Hui Pan
- Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, China.
| | - Yu-Jia Zeng
- Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, China.
| | - Wu-Xing Zhou
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Ke-Qiu Chen
- Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, China.
| | - Gang Zhang
- Institute of High Performance Computing, A*STAR Singapore, 138632, Singapore.
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7
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Bajaj A, Ali ME. Anti-ohmic nanoconductors: myth, reality and promise. Phys Chem Chem Phys 2023; 25:9607-9616. [PMID: 36942699 DOI: 10.1039/d3cp00366c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The recent accomplishment in the design of molecular nanowires characterized by increasing conductance with length has led to the origin of an extraordinary new family of molecular junctions referred to as "anti-ohmic" wires. Herein, this highly desirable, non-classical behavior, has been examined for molecules long-enough to exhibit pronounced diradical character in their ground state within the unrestricted DFT formalism with spin symmetry breaking. We demonstrate that highly conjugated acenes signal higher resistance in an open-shell singlet (OSS) configuration as compared to their closed-shell counterparts. This anomaly has been further proven for experimentally certified cumulene wires, which reveals phenomenal modulation in the transport characteristics such that an increasing conductance is observed in the closed-shell limit, while higher cumulenes in the OSS ground state yield regular decay of conductance.
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Affiliation(s)
- Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India.
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India.
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8
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Estimating the Number of Molecules in Molecular Junctions Merely Based on the Low Bias Tunneling Conductance at Variable Temperature. Int J Mol Sci 2022; 23:ijms232314985. [PMID: 36499309 PMCID: PMC9737784 DOI: 10.3390/ijms232314985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022] Open
Abstract
Temperature (T) dependent conductance G=G(T) data measured in molecular junctions are routinely taken as evidence for a two-step hopping mechanism. The present paper emphasizes that this is not necessarily the case. A curve of lnG versus 1/T decreasing almost linearly (Arrhenius-like regime) and eventually switching to a nearly horizontal plateau (Sommerfeld regime), or possessing a slope gradually decreasing with increasing 1/T is fully compatible with a single-step tunneling mechanism. The results for the dependence of G on T presented include both analytical exact and accurate approximate formulas and numerical simulations. These theoretical results are general, also in the sense that they are not limited, e.g., to the (single molecule electromigrated (SET) or large area EGaIn) fabrication platforms, which are chosen for exemplification merely in view of the available experimental data needed for analysis. To be specific, we examine in detail transport measurements for molecular junctions based on ferrocene (Fc). As a particularly important finding, we show how the present analytic formulas for G=G(T) can be utilized to compute the ratio f=Aeff/An between the effective and nominal areas of large area Fc-based junctions with an EGaIn top electrode. Our estimate of f≈0.6×10-4 is comparable with previously reported values based on completely different methods for related large area molecular junctions.
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9
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de Freitas Martins E, Scheicher RH, Rocha AR, Feliciano GT. A multiscale approach for electronic transport simulation of carbon nanostructures in aqueous solvent. Phys Chem Chem Phys 2022; 24:24404-24412. [PMID: 36189627 DOI: 10.1039/d2cp02474h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Theoretical works addressing electronic nano-devices operating in an aqueous environment often neglect solvent effects. In order to assess the role played by the polarization effects on the electronic transport properties of solvated graphene, for example in possible bio-sensing applications, we have used here a combination of polarizable force-field molecular dynamics, hybrid quantum mechanics/molecular mechanics (QM/MM) approach, density functional theory, and non-equilibrium Green's function method. We considered different solvation conditions, the presence of defects in graphene, as well as various choices for the partitions between the quantum and classical regions in QM/MM, in which we explicitly account for polarization effects. Our results show that the polarization effects on graphene lead to changes in the structure of interfacial water molecules which are more pronounced in the vicinity of defects. The presence of water leads to increased scattering due to the long-range charge interactions with graphene. At the same time, changes in the conductance due to polarization or salt concentration are found to be small, paving the way for robust electronic nano-devices operating in aqueous environments.
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Affiliation(s)
| | - Ralph Hendrik Scheicher
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden
| | - Alexandre Reily Rocha
- Institute of Theoretical Physics, São Paulo State University (UNESP), São Paulo, Brazil
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10
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Bishnoi B, Buerkle M, Nakamura H. Multi-scale electronics transport properties in non-ideal CVD graphene sheet. Sci Rep 2022; 12:11214. [PMID: 35780171 PMCID: PMC9250536 DOI: 10.1038/s41598-022-15098-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/17/2022] [Indexed: 11/10/2022] Open
Abstract
In this work, we benchmark non-idealities and variations in the two-dimensional graphene sheet. We have simulated more than two hundred graphene-based devices structure. We have simulated distorted graphene sheets and have included random, inhomogeneous, asymmetric out-of-plane surface corrugation and in-plane deformation corrugation in the sheet through autocorrelation function in the non-equilibrium Green's function (NEGF) framework to introduce random distortion in flat graphene. These corrugation effects inevitably appear in the graphene sheet due to background substrate roughness or the passivation encapsulation material morphology in the transfer step. We have examined the variation in density of state, propagating density of transmission modes, electronic band structure, electronic density, and hole density in those device structures. We have observed that the surface corrugation increases the electronic and hole density distribution variation across the device and creates electron-hole charge puddles in the sheet. This redistribution of microscopic charge in the sheet is due to the lattice fields' quantum fluctuation and symmetry breaking. Furthermore, to understand the impact of scattered charge distribution on the sheet, we simulated various impurity effects within the NEGF framework. The study's objective is to numerically simulate and benchmark numerous device design morphology with different background materials compositions to elucidate the electrical property of the sheet device.
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Affiliation(s)
- Bhupesh Bishnoi
- National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Computational Design of Advanced Functional Materials (CD-FMat), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan.
| | - Marius Buerkle
- National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Computational Design of Advanced Functional Materials (CD-FMat), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan
| | - Hisao Nakamura
- National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Computational Design of Advanced Functional Materials (CD-FMat), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan
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11
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Muthaiah R, Tarannum F, Danayat S, Annam RS, Nayal AS, Yedukondalu N, Garg J. The superior effect of edge functionalization relative to basal plane functionalization of graphene in enhancing the thermal conductivity of polymer-graphene nanocomposites - a combined molecular dynamics and Green's functions study. Phys Chem Chem Phys 2022; 24:14640-14650. [PMID: 35670366 DOI: 10.1039/d2cp00146b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To achieve polymer-graphene nanocomposites with high thermal conductivity (k), it is critically important to achieve efficient thermal coupling between graphene and the surrounding polymer matrix through effective functionalization schemes. In this work, we demonstrate that edge-functionalization of graphene nanoplatelets (GnPs) can enable a larger enhancement of effective thermal conductivity in polymer-graphene nanocomposites relative to basal plane functionalization. Effective thermal conductivity for the edge case is predicted, through molecular dynamics simulations, to be up to 48% higher relative to basal plane bonding for 35 wt% graphene loading with 10 layer thick nanoplatelets. The beneficial effect of edge bonding is related to the anisotropy of thermal transport in graphene, involving very high in-plane thermal conductivity (∼2000 W m-1 K-1) compared to the low out-of-plane thermal conductivity (∼10 W m-1 K-1). Likewise, in multilayer graphene nanoplatelets (GnPs), the thermal conductivity across the layers is even lower due to the weak van der Waals bonding between each pair of layers. Edge functionalization couples the polymer chains to the high in-plane thermal conduction pathway of graphene, thus leading to overall high thermal conductivity of the composite. Basal-plane functionalization, however, lowers the thermal resistance between the polymer and the surface graphene sheets of the nanoplatelet only, causing the heat conduction through inner layers to be less efficient, thus resulting in the basal plane scheme to be outperformed by the edge scheme. The present study enables fundamentally novel pathways for achieving high thermal conductivity polymer nanocomposites.
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Affiliation(s)
- Rajmohan Muthaiah
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
| | - Fatema Tarannum
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
| | - Swapneel Danayat
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
| | - Roshan Sameer Annam
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
| | - Avinash Singh Nayal
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
| | - N Yedukondalu
- Department of Geosciences, Stony Brook University, Stony Brook, New York 11794-2100, USA
| | - Jivtesh Garg
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, 73019, USA.
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12
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Bâldea I. Exact Analytic Formula for Conductance Predicting a Tunable Sommerfeld–Arrhenius Thermal Transition within a Single‐Step Tunneling Mechanism in Molecular Junctions Subject to Mechanical Stretching. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry Heidelberg University Im Neuenheimer Feld 229 D‐69120 Heidelberg Germany
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13
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Bâldea I. Are Asymmetric SAM‐Induced Work Function Modifications Relevant for Real Molecular Rectifiers? ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry Heidelberg University Im Neuenheimer Feld 229 Heidelberg D‐69120 Germany
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14
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Zeng YJ, Ding ZK, Pan H, Feng YX, Chen KQ. Nonequilibrium Green's function method for phonon heat transport in quantum system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:223001. [PMID: 35263716 DOI: 10.1088/1361-648x/ac5c21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 03/09/2022] [Indexed: 06/14/2023]
Abstract
Phonon heat transport property in quantum devices is of great interesting since it presents significant quantum behaviors. In the past few decades, great efforts have been devoted to establish the theoretical method for phonon heat transport simulation in nanostructures. However, modeling phonon heat transport from wavelike coherent regime to particlelike incoherent regime remains a challenging task. The widely adopted theoretical approach, such as molecular dynamics, semiclassical Boltzmann transport equation, captures quantum mechanical effects within different degrees of approximation. Among them, Non-equilibrium Green's function (NEGF) method has attracted wide attention, as its ability to perform full quantum simulation including many-body interactions. In this review, we summarized recent theoretical advances of phonon NEGF method and the applications on the numerical simulation for phonon heat transport in nanostructures. At last, the challenges of numerical simulation are discussed.
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Affiliation(s)
- Yu-Jia Zeng
- Department of Physics, School of Physics and Electronic Science, Hunan University, Changsha, People's Republic of China
| | - Zhong-Ke Ding
- Department of Physics, School of Physics and Electronic Science, Hunan University, Changsha, People's Republic of China
| | - Hui Pan
- Department of Physics, School of Physics and Electronic Science, Hunan University, Changsha, People's Republic of China
| | - Ye-Xin Feng
- Department of Physics, School of Physics and Electronic Science, Hunan University, Changsha, People's Republic of China
| | - Ke-Qiu Chen
- Department of Physics, School of Physics and Electronic Science, Hunan University, Changsha, People's Republic of China
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15
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Popoff A, Rech J, Jonckheere T, Raymond L, Grémaud B, Malherbe S, Martin T. Scattering theory of non-equilibrium noise and delta Tcurrent fluctuations through a quantum dot. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:185301. [PMID: 35120336 DOI: 10.1088/1361-648x/ac5200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 02/04/2022] [Indexed: 06/14/2023]
Abstract
We consider the non-equilibrium zero frequency noise generated by a temperature gradient applied on a device composed of two normal leads separated by a quantum dot. We recall the derivation of the scattering theory for non-equilibrium noise for a general situation where both a bias voltage and a temperature gradient can coexist and put it in a historical perspective. We provide a microscopic derivation of zero frequency noise through a quantum dot based on a tight binding Hamiltonian, which constitutes a generalization of the seminal result obtained for the current in the context of the Keldysh formalism. For a single level quantum dot, the obtained transmission coefficient entering the scattering formula for the non-equilibrium noise corresponds to a Breit-Wigner resonance. We compute the delta-Tnoise as a function of the dot level position, and for a broad range of values of the dot level width, in the Breit-Wigner case, for two relevant situations which were considered recently in two separate experiments. In the regime where the two reservoir temperatures are comparable, our gradient expansion shows that the delta-Tnoise is dominated by its quadratic contribution, and is minimal close to resonance. In the opposite regime where one reservoir is much colder, the gradient expansion fails and we find the noise to be typically linear in temperature before saturating. In both situations, we conclude with a short discussion of the case where both a voltage bias and a temperature gradient are present, in order to address the potential competition with thermoelectric effects.
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Affiliation(s)
- A Popoff
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
- Collège Tinomana Ebb de Teva I Uta, BP 15001 - 98726 Mataiea, Tahiti, French Polynesia
| | - J Rech
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
| | - T Jonckheere
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
| | - L Raymond
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
| | - B Grémaud
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
| | - S Malherbe
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
- Département de Physique, Ecole Normale Supérieure, 45 Rue d'Ulm, 75005 Paris, France
| | - T Martin
- Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France
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16
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da Silva C, Nisioka K, Moura-Moreira M, Macedo R, Del Nero J. Tunneling rules for electronic transport in 1-D systems. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1976427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- C.A.B. da Silva
- Faculdade de Física, Universidade Federal do Pará, Ananindeua, Brazil
| | - K.R. Nisioka
- Faculdade de Engenharia de Materiais, Universidade Federal do Pará, Ananindeua, Brazil
| | - M. Moura-Moreira
- Programa de Pós-Graduação em Engenharia Elétrica, Universidade Federal do Pará, Belém, Brazil
| | - R.F. Macedo
- Faculdade de Geologia, Universidade Federal do Pará, Belém, Brazil
| | - J. Del Nero
- Facudade de Física, Universidade Federal do Pará, Belém, Brazil
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17
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Silva FWN, Barros EB, Capaz RB. Oxygen effects on the electronic transport in stanene. NANOTECHNOLOGY 2021; 32:395201. [PMID: 34167095 DOI: 10.1088/1361-6528/ac0e6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
In this work, we study theoretically the structural, electronic and transport properties of oxidized stanene using a combination of density functional theory (DFT), quantum molecular dynamics and the Landauer-Büttiker theory for the ballistic transport. Our results clearly show that oxygen adsorb onto stanene surface in both molecular or atomic forms, thus causing considerable modifications to its electronic structure and transport properties. Nevertheless, our quantum conductance calculations reveal that, in spite of oxidation, stanene still remains a good conductor that might be applied as field effect transistors, gas sensors and other devices.
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Affiliation(s)
- F W N Silva
- Instituto Federal de Educação, Ciência e Tecnologia do Maranhão-Campus Alcântara, Maranhão, 65250-000, Brazil
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, 60455-900, Brazil
| | - E B Barros
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, 60455-900, Brazil
| | - Rodrigo B Capaz
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ, 21941-972, Brazil
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18
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Tuovinen R, van Leeuwen R, Perfetto E, Stefanucci G. Electronic transport in molecular junctions: The generalized Kadanoff-Baym ansatz with initial contact and correlations. J Chem Phys 2021; 154:094104. [PMID: 33685185 DOI: 10.1063/5.0040685] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The generalized Kadanoff-Baym ansatz (GKBA) offers a computationally inexpensive approach to simulate out-of-equilibrium quantum systems within the framework of nonequilibrium Green's functions. For finite systems, the limitation of neglecting initial correlations in the conventional GKBA approach has recently been overcome [Karlsson et al., Phys. Rev. B 98, 115148 (2018)]. However, in the context of quantum transport, the contacted nature of the initial state, i.e., a junction connected to bulk leads, requires a further extension of the GKBA approach. In this work, we lay down a GKBA scheme that includes initial correlations in a partition-free setting. In practice, this means that the equilibration of the initially correlated and contacted molecular junction can be separated from the real-time evolution. The information about the contacted initial state is included in the out-of-equilibrium calculation via explicit evaluation of the memory integral for the embedding self-energy, which can be performed without affecting the computational scaling with the simulation time and system size. We demonstrate the developed method in carbon-based molecular junctions, where we study the role of electron correlations in transient current signatures.
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Affiliation(s)
- Riku Tuovinen
- QTF Centre of Excellence, Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - Robert van Leeuwen
- Department of Physics, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Enrico Perfetto
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Gianluca Stefanucci
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
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19
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Pang ZX, Zhao YC, Ji WX, Wang Y, Li P. A novel spin-valley-coupled nodal-ring semimetal in single-layer Ta 2C 3. Phys Chem Chem Phys 2021; 23:12280-12287. [PMID: 34013913 DOI: 10.1039/d1cp01424b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nodal-ring semimetals with band crossing are the new type of quantum materials that have attracted considerable interest from scholars for research. In general, the spin-orbit coupling (SOC) effect opens a band gap at the Dirac point. Therefore, finding 2D nodal-ring semimetals with resistance to SOC has more challenges. Based on first-principles calculations, we propose here that the two-dimensional (2D) Ta2C3 monolayer is a novel nodal-ring semimetal. In particular, Ta2C3 forms six closed rings in the Brillouin zone (BZ) with SOC, which originates from the dxy,x2-y2 orbitals of Ta and the pz orbitals of C. The nodal-ring bands at the K point in Ta2C3 exhibits characteristics of valley splitting and spin polarization due to the breaking of inversion symmetry and SOC. The masximal spin-splitting at the K point is as large as 268.87 meV and 61.90 meV for the conduction band minimum (CBM) and valence band maximum (VBM), respectively. The massless Dirac fermions in the non-equivalent valley have the opposite Berry curvature and spin moment. Therefore, 2D Ta2C3 is novel spin-valley-coupled nodal-ring semimetal. In addition, we found interesting negative differential resistance effects when calculating its transport properties. Our results not only provide an ideal platform for studying the combination of new physical properties, spintronics and valleytronics, but also open the way for designing low-power and fast-transport electronic devices.
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Affiliation(s)
- Zhao-Xia Pang
- School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
| | - Yong-Chun Zhao
- School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
| | - Wei-Xiao Ji
- School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
| | - Yong Wang
- School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
| | - Ping Li
- School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
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20
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Zwolak M. Analytic expressions for the steady-state current with finite extended reservoirs. J Chem Phys 2020; 153:224107. [PMID: 33317280 PMCID: PMC8356363 DOI: 10.1063/5.0029223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Open-system simulations of quantum transport provide a platform for the study of true steady states, Floquet states, and the role of temperature, time dynamics, and fluctuations, among other physical processes. They are rapidly gaining traction, especially techniques that revolve around "extended reservoirs," a collection of a finite number of degrees of freedom with relaxation that maintains a bias or temperature gradient, and have appeared under various guises (e.g., the extended or mesoscopic reservoir, auxiliary master equation, and driven Liouville-von Neumann approaches). Yet, there are still a number of open questions regarding the behavior and convergence of these techniques. Here, we derive general analytical solutions, and associated asymptotic analyses, for the steady-state current driven by finite reservoirs with proportional coupling to the system/junction. In doing so, we present a simplified and unified derivation of the non-interacting and many-body steady-state currents through arbitrary junctions, including outside of proportional coupling. We conjecture that the analytic solution for proportional coupling is the most general of its form for isomodal relaxation (i.e., relaxing proportional coupling will remove the ability to find compact, general analytical expressions for finite reservoirs). These results should be of broad utility in diagnosing the behavior and implementation of extended reservoir and related approaches, including the convergence to the Landauer limit (for non-interacting systems) and the Meir-Wingreen formula (for many-body systems).
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Affiliation(s)
- Michael Zwolak
- Biophysical and Biomedical Measurement Group, Microsystems and Nanotechnology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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21
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Zöllner MS, Saghatchi A, Mujica V, Herrmann C. Influence of Electronic Structure Modeling and Junction Structure on First-Principles Chiral Induced Spin Selectivity. J Chem Theory Comput 2020; 16:7357-7371. [PMID: 33167619 DOI: 10.1021/acs.jctc.0c00621] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We have carried out a comprehensive study of the influence of electronic structure modeling and junction structure description on the first-principles calculation of the spin polarization in molecular junctions caused by the chiral induced spin selectivity (CISS) effect. We explore the limits and the sensitivity to modeling decisions of a Landauer/Green's function/two-component density functional theory approach to CISS. We find that although the CISS effect is entirely attributed in the literature to molecular spin filtering, spin-orbit coupling being partially inherited from the metal electrodes plays an important role in our calculations on ideal carbon helices, even though this effect cannot explain the experimental conductance results. Its magnitude depends considerably on the shape, size, and material of the metal clusters modeling the electrodes. Also, a pronounced dependence on the specific description of exchange interaction and spin-orbit coupling is manifest in our approach. This is important because the interplay between exchange effects and spin-orbit coupling may play an important role in the description of the junction magnetic response. Our calculations are relevant for the whole field of spin-polarized electron transport and electron transfer, because there is still an open discussion in the literature about the detailed underlying mechanism and the magnitude of physical parameters that need to be included to achieve a consistent description of the CISS effect: seemingly good quantitative agreement between simulation and the experiment can be caused by error compensation, because spin polarization as contained in a Landauer/Green's function/two-component density functional theory approach depends strongly on computational and structural parameters.
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Affiliation(s)
| | - Aida Saghatchi
- Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Vladimiro Mujica
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States.,Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center (DIPC), Donostia, Euskadi P.K. 1072, 20080, Spain
| | - Carmen Herrmann
- Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
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22
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Liu C, Fu Q, Gu Z, Lu P. The reservoir area dependent thermal transport at the nanoscale interface. Phys Chem Chem Phys 2020; 22:22016-22022. [PMID: 32975247 DOI: 10.1039/d0cp04001k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reservoir area dependent thermal transport at nanoscale two-dimensional and one-dimensional interfaces is investigated by the non-equilibrium Green's function method. For the two-dimensional nanoscale interface composed of graphene sheets, the reservoir area is identical to the contact area S at the interface. As S increases from few atoms, the interfacial thermal conductance σ per S (Λ = σ/S) is negatively dependent on S due to the decrease of phonon transmission per S. With S increasing to several square nanometers, Λ converges to a constant value. However, for the one-dimensional nanoscale interface composed of nested carbon nanotubes (NCNTs), it is σ instead of Λ that converges to a constant value because the reservoir in one-dimensional nanoscale NCNTs has a fixed area, which can only provide finite transport channels. There are two competitive factors influencing the thermal transport at the interface in the NCNT model. One is phonon mode coupling and the other is phonon scattering. These two factors lead to an interesting trend of σ that as the overlap between NCNTs increases, σ increases at first and then decreases and converges to a constant value. These findings indicate that the thermal transport behavior has a strong dependence on the contact details and reservoir area at the nanoscale interface.
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Affiliation(s)
- Chenhan Liu
- Engineering Laboratory for Energy System Process Conversion & Emission Reduction Technology of Jiangsu Province, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, 210042, P. R. China.
| | - Qiang Fu
- School of Mechanical and Electrical Engineering, Shenzhen Polytechnic, Shenzhen 518005, P. R. China
| | - Zhongzhu Gu
- Engineering Laboratory for Energy System Process Conversion & Emission Reduction Technology of Jiangsu Province, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, 210042, P. R. China.
| | - Ping Lu
- Engineering Laboratory for Energy System Process Conversion & Emission Reduction Technology of Jiangsu Province, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, 210042, P. R. China.
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23
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Martinez A, Barker JR. Quantum Transport in a Silicon Nanowire FET Transistor: Hot Electrons and Local Power Dissipation. MATERIALS (BASEL, SWITZERLAND) 2020; 13:ma13153326. [PMID: 32722649 PMCID: PMC7435733 DOI: 10.3390/ma13153326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/08/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
A review and perspective is presented of the classical, semiclassical and fully quantum routes to the simulation of electrothermal phenomena in ultrascaled silicon nanowire fieldeffect transistors. It is shown that the physics of ultrascaled devices requires at least a coupled electron quantum transport semiclassical heat equation model outlined here. The importance of the local density of states (LDOS) is discussed from classical to fully quantum versions. It is shown that the minimal quantum approach requires selfconsistency with the Poisson equation and that the electronic LDOS must be determined within at least the selfconsistent Born approximation. To bring in this description and to provide the energy resolved local carrier distributions it is necessary to adopt the nonequilibrium Green function (NEGF) formalism, briefly surveyed here. The NEGF approach describes quantum coherent and dissipative transport, Pauli exclusion and nonequilibrium conditions inside the device. There are two extremes of NEGF used in the community. The most fundamental is based on coupled equations for the Green functions electrons and phonons that are computed at the atomically resolved level within the nanowire channel and into the surrounding device structure using a tight binding Hamiltonian. It has the advantage of treating both the nonequilibrium heat flow within the electron and phonon systems even when the phonon energy distributions are not described by a temperature model. The disadvantage is the grand challenge level of computational complexity. The second approach, that we focus on here, is more useful for fast multiple simulations of devices important for TCAD (Technology Computer Aided Design). It retains the fundamental quantum transport model for the electrons but subsumes the description of the energy distribution of the local phonon subsystem statistics into a semiclassical Fourier heat equation that is sourced by the local heat dissipation from the electron system. It is shown that this selfconsistent approach retains the salient features of the fullscale approach. For focus, we outline our electrothermal simulations for a typical narrow Si nanowire gate allaround fieldeffect transistor. The selfconsistent Born approximation is used to describe electronphonon scattering as the source of heat dissipation to the lattice. We calculated the effect of the device selfheating on the current voltage characteristics. Our fast and simpler methodology closely reproduces the results of a more fundamental computeintensive calculations in which the phonon system is treated on the same footing as the electron system. We computed the local power dissipation and "local lattice temperature" profiles. We compared the selfheating using hot electron heating and the Joule heating, i.e., assuming the electron system was in local equilibrium with the potential. Our simulations show that at low bias the source region of the device has a tendency to cool down for the case of the hot electron heating but not for the case of Joule heating. Our methodology opens the possibility of studying thermoelectricity at nanoscales in an accurate and computationally efficient way. At nanoscales, coherence and hot electrons play a major role. It was found that the overall behaviour of the electron system is dominated by the local density of states and the scattering rate. Electrons leaving the simulated drain region were found to be far from equilibrium.
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Affiliation(s)
- Antonio Martinez
- College of Engineering, Swansea University, Engineering East, Fabian Way, Crymlyn Burroughs, Swansea SA1 8EN, UK
| | - John R. Barker
- James Watt School of Engineering, College of Science and Engineering, University of Glasgow, Glasgow G12 8LT, Scotland, UK;
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24
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Keshtan MAM, Esmaeilzadeh M. Tight-binding Hamiltonian considering up to the third nearest neighbours for trans polyacetylene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:285401. [PMID: 32155603 DOI: 10.1088/1361-648x/ab7e55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Utilizing the linear combination of atomic orbitals in the Slater-Koster approach in combination with the density functional theory band structure data, a new tight-binding Hamiltonian up to the third nearest neighbours for the dimerized trans polyacetylene is proposed. The effects of strain are also considered in the Hamiltonian by varying the distance between two successive CH groups along the molecular symmetry axis. Using this new Hamiltonian and exploiting the Green's function method in the framework of the Landauer-Büttiker formalism, the electronic transport properties in a trans polyacetylene chain in the presence and absence of strain are studied. It is shown that at a peculiar value of compression strain, the electron conductance shifts 0.27 eV in energy which is an exploitable magnitude for straintronic applications of the trans polyacetylene specially as strain sensors and strain switches.
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Affiliation(s)
- M Ali M Keshtan
- Department of Physics, Iran University of Science and Technology, Narmak, Tehran 16844, Iran
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25
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Organic Spintronics: A Theoretical Investigation of a Graphene-Porphyrin Based Nanodevice. MAGNETOCHEMISTRY 2020. [DOI: 10.3390/magnetochemistry6020027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Spintronics is one of the most exciting applications of graphene-based devices. In this work Density Functional Theory is used to study a nanojunction consisting of two semi-infinite graphene electrodes contacted with an iron-porphyrin (FeP) molecule, which plays the role of spin filter for the incoming unpolarized electrons. The graphene-FeP contact closely resembles the recently synthesized porphyrin-decorated graphene [He et al., Nat. Chem. 2017, 9, 33–38]. The analysis of the spectral properties of the system shows a variation of the orbital occupancy with respect to the isolated FeP molecule and an hybridization with the delocalized states of the substrate, while the overall magnetic moment remains unchanged. Doping the electrodes with boron or nitrogen atoms induces a relevant rearrangement in the electronic structure of the junction. Upon B doping the current becomes significantly spin polarized, while N doping induces a marked Negative Differential Resistivity effect. We have also investigated the possible exploitation of the FeP junction as a gas sensor device. We demonstrate that the interaction of CO and O2 molecules with the Fe atom, while being strong enough to be stable at room temperature (2.0 eV and 1.1 eV, respectively), induces only minor effects on the electronic properties of the junction. Interestingly, a quenching of the spin polarization of the current is observed in the B-doped system.
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26
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Chu W, Li X. Reduced-Order Modeling Approach for Electron Transport in Molecular Junctions. J Chem Theory Comput 2020; 16:3746-3756. [DOI: 10.1021/acs.jctc.9b01090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Weiqi Chu
- Department of Mathematics, University of California, Los Angeles, Los Angeles, CA 90095, United States
- Department of Mathematics, Pennsylvania State University, University Park, PA 16802, United States
| | - Xiantao Li
- Department of Mathematics, Pennsylvania State University, University Park, PA 16802, United States
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27
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Boumrar H, Hamidi M, Zenia H, Lounis S. Equivalence of wave function matching and Green's functions methods for quantum transport: generalized Fisher-Lee relation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:355302. [PMID: 32289759 DOI: 10.1088/1361-648x/ab88f5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
We present a proof of an exact equivalence of the two approaches that are most used in computing conductance in quantum electron and phonon transport: the wave function matching and Green's functions methods. We can obtain all the quantities defined in one method starting from those obtained in the other. This completes and illuminates the work started by Ando (1991Phys. Rev. B448017) and continued later by Khomyakovet al(2005Phys. Rev. B72035450). The aim is to allow for solving the transport problem with whichever approach fits most the system at hand. One major corollary of the proven equivalence is our derivation of a generalized Fisher-Lee formula for resolving the transmission function into individual phonon mode contributions. As an illustration, we applied our method to a simple model to highlight its accuracy and simplicity.
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Affiliation(s)
- Hocine Boumrar
- Laboratoire de Physique et Chimie Quantique, FacultÉ des Sciences, UniversitÉ Mouloud Mammeri Tizi-Ouzou BP 17 RP, 15000 Tizi-Ouzou, Algeria
| | - Mahdi Hamidi
- Laboratoire de Physique et Chimie Quantique, FacultÉ des Sciences, UniversitÉ Mouloud Mammeri Tizi-Ouzou BP 17 RP, 15000 Tizi-Ouzou, Algeria
| | - Hand Zenia
- Laboratoire de Physique et Chimie Quantique, FacultÉ des Sciences, UniversitÉ Mouloud Mammeri Tizi-Ouzou BP 17 RP, 15000 Tizi-Ouzou, Algeria
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
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28
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Ali M Keshtan M, Esmaeilzadeh M. Topological spintronics in a polyacetylene molecule device. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:345302. [PMID: 32209751 DOI: 10.1088/1361-648x/ab832a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 03/25/2020] [Indexed: 06/10/2023]
Abstract
Using the Su-Schrieffer-Heeger Hamiltonian and exploiting the Green's function method in the framework of the Landauer-Büttiker formalism, the topological and spin dependent electron transport properties of a trans polyacetylene molecule are studied. It is found that molecules with the intracell single carbon-carbon bonding and the even number of monomers in their chains have two edge states and possess topological properties though their Hamiltonians do not respect the chiral symmetry. A perpendicular exchange magnetic field and two perpendicular and transverse electric fields are used to induce and manipulate the quantum spin dependent electron transport properties. The exchange field induces the spin polarization in different electron energy regions which are expanded by stronger exchange fields. Therefore this proposed device works as a perfect spin filter. The spin polarization can be manipulated by applying the perpendicular electric field and remains robust against the transverse electric field variations.
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Affiliation(s)
- M Ali M Keshtan
- Department of physics, Iran University of Science and Technology, Narmak, Tehran 16844, Iran
| | - Mahdi Esmaeilzadeh
- Department of physics, Iran University of Science and Technology, Narmak, Tehran 16844, Iran
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29
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Shubin NM, Gorbatsevich AA, Krasnikov GY. Non-Hermitian Hamiltonians and Quantum Transport in Multi-Terminal Conductors. ENTROPY 2020; 22:e22040459. [PMID: 33286233 PMCID: PMC7516943 DOI: 10.3390/e22040459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 02/02/2023]
Abstract
We study the transport properties of multi-terminal Hermitian structures within the non-equilibrium Green's function formalism in a tight-binding approximation. We show that non-Hermitian Hamiltonians naturally appear in the description of coherent tunneling and are indispensable for the derivation of a general compact expression for the lead-to-lead transmission coefficients of an arbitrary multi-terminal system. This expression can be easily analyzed, and a robust set of conditions for finding zero and unity transmissions (even in the presence of extra electrodes) can be formulated. Using the proposed formalism, a detailed comparison between three- and two-terminal systems is performed, and it is shown, in particular, that transmission at bound states in the continuum does not change with the third electrode insertion. The main conclusions are illustratively exemplified by some three-terminal toy models. For instance, the influence of the tunneling coupling to the gate electrode is discussed for a model of quantum interference transistor. The results of this paper will be of high interest, in particular, within the field of quantum design of molecular electronic devices.
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Affiliation(s)
- Nikolay M. Shubin
- P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia;
- JSC Molecular Electronics Research Institute, Zelenograd, Moscow 124460, Russia;
| | - Alexander A. Gorbatsevich
- P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia;
- JSC Molecular Electronics Research Institute, Zelenograd, Moscow 124460, Russia;
- Correspondence:
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30
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Zöllner MS, Varela S, Medina E, Mujica V, Herrmann C. Insight into the Origin of Chiral-Induced Spin Selectivity from a Symmetry Analysis of Electronic Transmission. J Chem Theory Comput 2020; 16:2914-2929. [DOI: 10.1021/acs.jctc.9b01078] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Solmar Varela
- School of Chemical Sciences and Engineering, Yachay Tech University, 100119 Urcuquı́, Ecuador
| | - Ernesto Medina
- Yachay Tech University, School of Physical Sciences and Nanotechnology, 100119 Urcuquı́, Ecuador
| | - Vladimiro Mujica
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA
| | - Carmen Herrmann
- Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
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31
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Rams MM, Zwolak M. Breaking the Entanglement Barrier: Tensor Network Simulation of Quantum Transport. PHYSICAL REVIEW LETTERS 2020; 124:137701. [PMID: 32302169 PMCID: PMC7654706 DOI: 10.1103/physrevlett.124.137701] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 10/08/2019] [Accepted: 02/21/2020] [Indexed: 06/11/2023]
Abstract
The recognition that large classes of quantum many-body systems have limited entanglement in the ground and low-lying excited states led to dramatic advances in their numerical simulation via so-called tensor networks. However, global dynamics elevates many particles into excited states, and can lead to macroscopic entanglement and the failure of tensor networks. Here, we show that for quantum transport-one of the most important cases of this failure-the fundamental issue is the canonical basis in which the scenario is cast: When particles flow through an interface, they scatter, generating a "bit" of entanglement between spatial regions with each event. The frequency basis naturally captures that-in the long-time limit and in the absence of inelastic scattering-particles tend to flow from a state with one frequency to a state of identical frequency. Recognizing this natural structure yields a striking-potentially exponential in some cases-increase in simulation efficiency, greatly extending the attainable spatial and time scales, and broadening the scope of tensor network simulation to hitherto inaccessible classes of nonequilibrium many-body problems.
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Affiliation(s)
- Marek M. Rams
- Jagiellonian University, Marian Smoluchowski Institute of Physics, Łojasiewicza 11, 30-348 Kraków, Poland
| | - Michael Zwolak
- Biophysics Group, Microsystems and Nanotechnology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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32
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Bâldea I. Evidence That Molecules in Molecular Junctions May Not Be Subject to the Entire External Perturbation Applied to Electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1329-1337. [PMID: 31957453 DOI: 10.1021/acs.langmuir.9b03430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Whether molecules forming molecular junctions are really subject to the entire external perturbation applied to electrodes is an important issue, but so far, it has not received adequate consideration in the literature. In this paper, we demonstrate that, out of the temperature difference ΔTelectr between electrodes applied in thermopower measurements, molecules only feel a significantly smaller temperature difference (ΔTmolec < ΔTelectr). Rephrasing, temperature drops at metal-molecule interfaces are substantial. Our theoretical analysis to address this problem of fundamental importance for surface science is based on experimental data collected via ultraviolet photoelectron spectroscopy, transition voltage spectroscopy, and Seebeck coefficient measurements. An important practical consequence of the presently reported finding is that the energetic alignment of the frontier molecular orbital (HOMO or LUMO) of the embedded molecules with respect to the metallic Fermi level position deduced from thermopower data-and this is frequently the case in current studies of molecular electronics-is substantially overestimated. Another important result presented here is that, unlike the exponential length dependence characterizing electric conduction (which is a fingerprint for quantum tunneling), thermal conduction through the molecules considered (oligophenylene thiols and alkane thiols) exhibits a length dependence compatible with classical physics.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie , Universität Heidelberg , Im Neuenheimer Feld 229 , D-69120 Heidelberg , Germany
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33
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Li Z, Xiong S, Sievers C, Hu Y, Fan Z, Wei N, Bao H, Chen S, Donadio D, Ala-Nissila T. Influence of thermostatting on nonequilibrium molecular dynamics simulations of heat conduction in solids. J Chem Phys 2019; 151:234105. [PMID: 31864248 DOI: 10.1063/1.5132543] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nonequilibrium molecular dynamics (NEMD) has been extensively used to study thermal transport at various length scales in many materials. In this method, two local thermostats at different temperatures are used to generate a nonequilibrium steady state with a constant heat flux. Conventionally, the thermal conductivity of a finite system is calculated as the ratio between the heat flux and the temperature gradient extracted from the linear part of the temperature profile away from the local thermostats. Here, we show that, with a proper choice of the thermostat, the nonlinear part of the temperature profile should actually not be excluded in thermal transport calculations. We compare NEMD results against those from the atomistic Green's function method in the ballistic regime and those from the homogeneous nonequilibrium molecular dynamics method in the ballistic-to-diffusive regime. These comparisons suggest that in all the transport regimes, one should directly calculate the thermal conductance from the temperature difference between the heat source and sink and, if needed, convert it into the thermal conductivity by multiplying it with the system length. Furthermore, we find that the Langevin thermostat outperforms the Nosé-Hoover (chain) thermostat in NEMD simulations because of its stochastic and local nature. We show that this is particularly important for studying asymmetric carbon-based nanostructures, for which the Nosé-Hoover thermostat can produce artifacts leading to unphysical thermal rectification.
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Affiliation(s)
- Zhen Li
- Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
| | - Shiyun Xiong
- Functional Nano and Soft Materials Laboratory (FUNSOM) and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 215123 Suzhou, People's Republic of China
| | - Charles Sievers
- Department of Chemistry, University of California at Davis, One Shields Ave., Davis, California 95616, USA
| | - Yue Hu
- University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zheyong Fan
- School of Mathematics and Physics, Bohai University, Jinzhou, China
| | - Ning Wei
- Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
| | - Hua Bao
- University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shunda Chen
- Department of Chemistry, University of California at Davis, One Shields Ave., Davis, California 95616, USA
| | - Davide Donadio
- Department of Chemistry, University of California at Davis, One Shields Ave., Davis, California 95616, USA
| | - Tapio Ala-Nissila
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Espoo, Finland
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34
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Wei F, Yu S. The bond charge current in the monolayer graphene superlattice with hopping beyond nearest neighbor. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:485703. [PMID: 31469101 DOI: 10.1088/1361-648x/ab3074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this paper, we systematically investigate the transportation properties of the zigzag nano-ribbon graphene in a local potential barrier/well with electrons hopping between and beyond nearest neighbor. When the local potential is present, the conductance exhibits novel periodic oscillation plateaus around increasing quantized conductance. The oscillation plateau hops down with the quantized conductance until vanishes with increasing local potential barrier. Furthermore, when a small voltage is applied between the two terminals of the conductor, the local current presents periodic oscillation in the barrier region. In contrast, when a local potential well is applied, the conductance shows irregular oscillation, exhibiting incommensurate oscillations of local current inside and outside the well. Finally, similar phenomena persists when more local potentials are applied to the system. We expect our studies can facilitate the design of relevant electronic devices.
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Affiliation(s)
- Fan Wei
- Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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35
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Rojas WY, Villegas CEP, Rocha AR. Ab initio modelling of spin relaxation lengths in disordered graphene nanoribbons. Phys Chem Chem Phys 2019; 21:26027-26032. [PMID: 31701103 DOI: 10.1039/c9cp04054d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The spin-dependent transport properties of armchair graphene nanoribbons in the presence of extrinsic spin-orbit coupling induced by a random distribution of nickel adatoms is studied. By combining a recursive Green's function formalism with density functional theory, we explore the influence of ribbon length and metal adatom concentration on the conductance. At a given length, we observed a significant enhancement of the spin-flip channel around resonances and at energies right above the Fermi level. We also estimate the spin-relaxation length, finding values on the order of tens of micrometers at low Ni adatom concentrations. This study is conducted at singular ribbon lengths entirely from fully ab initio methods, providing indirectly evidence that the Dyakonov-Perel spin relaxation mechanism might be the dominant at low concentrations as well as the observation of oscillations in the spin-polarization.
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Affiliation(s)
- Wudmir Y Rojas
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, Brazil
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36
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Hirsbrunner MR, Philip TM, Basa B, Kim Y, Jip Park M, Gilbert MJ. A review of modeling interacting transient phenomena with non-equilibrium Green functions. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:046001. [PMID: 30641508 DOI: 10.1088/1361-6633/aafe5f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
As experimental probes have matured to observe ultrafast transient and high frequency responses of materials and devices, so to have the theoretical methods to numerically and analytically simulate time- and frequency-resolved transport. In this review article, we discuss recent progress in the development of the time-dependent and frequency-dependent non-equilibrium Green function (NEGF) technique. We begin with an overview of the theoretical underpinnings of the underlying Kadanoff-Baym equations and derive the fundamental NEGF equations in the time and frequency domains. We discuss how these methods have been applied to a variety of condensed matter systems such as molecular electronics, nanoscale transistors, and superconductors. In addition, we survey the application of NEGF in fields beyond condensed matter, where it has been used to study thermalization in ultra-cold atoms and to understand leptogenesis in the early universe. Throughout, we pay special attention to the challenges of incorporating contacts and interactions, as the NEGF method is uniquely capable of accounting for such features.
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Affiliation(s)
- Mark R Hirsbrunner
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
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37
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de Freitas Martins E, Troiano Feliciano G, Hendrik Scheicher R, Reily Rocha A. Simulating DNA Chip Design Using All-Electronic Graphene-Based Substrates. Molecules 2019; 24:molecules24050951. [PMID: 30857133 PMCID: PMC6429485 DOI: 10.3390/molecules24050951] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 11/16/2022] Open
Abstract
In this paper, we present a theoretical investigation of an all-electronic biochip based on graphene to detect DNA including a full dynamical treatment for the environment. Our proposed device design is based on the changes in the electronic transport properties of graphene interacting with DNA strands under the effect of the solvent. To investigate these systems, we applied a hybrid methodology, combining quantum and classical mechanics (QM/MM) coupled to non-equilibrium Green’s functions, allowing for the calculations of electronic transport. Our results show that the proposed device has high sensitivity towards the presence of DNA, and, combined with the presence of a specific DNA probe in the form of a single-strand, it presents good selectivity towards specific nucleotide sequences.
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Affiliation(s)
- Ernane de Freitas Martins
- Institute of Theoretical Physics, São Paulo State University (UNESP), Campus São Paulo, 01140-070 São Paulo, Brazil.
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden.
| | - Gustavo Troiano Feliciano
- Institute of Chemistry, São Paulo State University (UNESP), Campus Araraquara, 14800-060 Araraquara, Brazil.
| | - Ralph Hendrik Scheicher
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden.
| | - Alexandre Reily Rocha
- Institute of Theoretical Physics, São Paulo State University (UNESP), Campus São Paulo, 01140-070 São Paulo, Brazil.
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38
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Panasyuk GY, Yerkes KL, Haugan TJ. Size effects in energy transport between thermal contacts mediated by nanoparticles. Phys Rev E 2019; 99:032141. [PMID: 30999472 DOI: 10.1103/physreve.99.032141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Indexed: 11/07/2022]
Abstract
We investigate size effects in phononic energy transport in a system of two nanoparticles interconnected by a molecule and attached to thermal contacts also by molecules. In the considered closed system, the nanoparticles and contacts are described by ensembles of finite numbers of harmonic oscillators within the Drude-Ullersma model. The macroscopic character of the contacts is simulated by a large value of the ratio Δ/Δ_{B}=n (n>100) of mode spacings Δ and Δ_{B} corresponding to the nanoparticles and contacts, respectively. Quasistatic energy transport on the timescale Δ^{-1} is investigated. Equations describing the dynamics of the averaged eigenmode energies that belong to the nanoparticles and contacts are derived and solved. The resulting expressions for the energy current exiting (entering) the contacts as well as the energy current between the nanoparticles are obtained and investigated. The latter current accounts for energy accumulation by (depletion from) the nanoparticles. The finite size effects result in reversibility features and peculiarities at time moments t=2πℓΔ^{-1} for non-negative integers ℓ. They are qualitatively the same as in a previously studied system of two equal nanoparticles mediated by a molecule, despite the presence of the macroscopic contacts. The thermal conductance of the whole nanojunction is derived and explored. The energy currents and thermal conductance of the nanojunction in a case when its parameters are known from the experiment are computed using the developed model.
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Affiliation(s)
- George Y Panasyuk
- Aerospace Systems Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA.,UES, Inc., 4401 Dayton-Xenia Road, Dayton, Ohio 45432, USA
| | - Kirk L Yerkes
- Aerospace Systems Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - Timothy J Haugan
- Aerospace Systems Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
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39
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Rojas WY, Villegas CEP, Rocha AR. Spin-orbit coupling prevents spin channel suppression of transition metal atoms on armchair graphene nanoribbons. Phys Chem Chem Phys 2018; 20:29826-29832. [PMID: 30467570 DOI: 10.1039/c8cp05337e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the spin-dependent electronic and transport properties of armchair graphene nanoribbons including spin-orbit coupling due to the presence of nickel and iridium adatoms by using ab initio calculations within the spin-polarized density functional theory and non-equilibrium Green's function formalism. Our results indicate that the intensity of the spin-flip precession is a direct consequence of the relaxed adsorption sites of the adatoms. We point out that d orbitals of Ni and Ir result in strong dependence on the spin-conserved and spin-flip transmission probabilities. In particular, we show that the presence of spin-orbit coupling can lead to an enhancement of the transmission probabilities especially around resonances arising due to weak coupling with specific orbitals.
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Affiliation(s)
- W Y Rojas
- School of Electronic Engineering, Bangor University, Bangor LL57 1UT, UK
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40
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Ganguly S, Basu S, Maiti SK. Controlled engineering of spin-polarized transport properties in a zigzag graphene nanojunction. ACTA ACUST UNITED AC 2018. [DOI: 10.1209/0295-5075/124/17005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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41
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Gorbatsevich AA, Krasnikov GY, Shubin NM. [Formula: see text]-symmetric interference transistor. Sci Rep 2018; 8:15780. [PMID: 30361561 PMCID: PMC6202334 DOI: 10.1038/s41598-018-34132-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/07/2018] [Indexed: 11/12/2022] Open
Abstract
We present a model of the molecular transistor, operation of which is based on the interplay between two physical mechanisms, peculiar to open quantum systems that act in concert: [Formula: see text] -symmetry breaking corresponding to coalescence of resonances at the exceptional point of the molecule, connected to the leads, and Fano-Feshbach antiresonance. This switching mechanism can be realised in particular in a special class of molecules with degenerate energy levels, e.g. diradicals, which possess mirror symmetry. At zero gate voltage infinitesimally small interaction of the molecule with the leads breaks the [Formula: see text] -symmetry of the system that, however, can be restored by application of the gate voltage preserving the mirror symmetry. [Formula: see text] -symmetry broken state at zero gate voltage with minimal transmission corresponds to the "off" state while the [Formula: see text] -symmetric state at non-zero gate voltage with maximum transmission - to the "on" state. At zero gate voltage energy of the antiresonance coincides with exceptional point. We construct a model of an all-electrical molecular switch based on such transistors acting as a conventional CMOS inverter and show that essentially lower power consumption and switching energy can be achieved, compared to the CMOS analogues.
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Affiliation(s)
- Alexander A. Gorbatsevich
- P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Division of solid state physics, Moscow, 119991 Russia
- JSC Molecular Electronics Research Institute, Zelenograd, Moscow 124460 Russia
| | | | - Nikolay M. Shubin
- P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Division of solid state physics, Moscow, 119991 Russia
- JSC Molecular Electronics Research Institute, Zelenograd, Moscow 124460 Russia
- Department of quantum physics and nanoelectronics, National Research University of Electronic Technology, Zelenograd, Moscow 124498 Russia
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42
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Aprojanz J, Power SR, Bampoulis P, Roche S, Jauho AP, Zandvliet HJW, Zakharov AA, Tegenkamp C. Ballistic tracks in graphene nanoribbons. Nat Commun 2018; 9:4426. [PMID: 30356162 PMCID: PMC6200825 DOI: 10.1038/s41467-018-06940-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 10/05/2018] [Indexed: 11/28/2022] Open
Abstract
High quality graphene nanoribbons epitaxially grown on the sidewalls of silicon carbide (SiC) mesa structures stand as key building blocks for graphene-based nanoelectronics. Such ribbons display 1D single-channel ballistic transport at room temperature with exceptionally long mean free paths. Here, using spatially-resolved two-point probe (2PP) measurements, we selectively access and directly image a range of individual transport modes in sidewall ribbons. The signature of the independently contacted channels is a sequence of quantised conductance plateaus for different probe positions. These result from an interplay between edge magnetism and asymmetric terminations at opposite ribbon edges due to the underlying SiC structure morphology. Our findings demonstrate a precise control of transport through multiple, independent, ballistic tracks in graphene-based devices, opening intriguing pathways for quantum information device concepts.
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Affiliation(s)
- Johannes Aprojanz
- Institut für Physik, Technische Universität Chemnitz, 09126, Chemnitz, Germany
| | - Stephen R Power
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193, Barcelona (Cerdanyola del Vallès), Spain
- Universitat Autònoma de Barcelona, 08193, Bellaterra (Cerdanyola del Vallès), Spain
- School of Physics, Trinity College Dublin, Dublin, 2, Ireland
| | - Pantelis Bampoulis
- Physics of Interfaces and Nanomaterials, MESA+Institute for Nanotechnology, University of Twente, 7522 NH, Enschede, The Netherlands
- Institut für Festkörperphysik, Leibniz Universität Hannover, 30167, Hannover, Germany
| | - Stephan Roche
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193, Barcelona (Cerdanyola del Vallès), Spain
- ICREA, Institució Catalana de Recerca i Estudis Avançats, 08070, Barcelona, Spain
| | - Antti-Pekka Jauho
- Center for Nanostructured Graphene (CNG), DTU Nanotech, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Harold J W Zandvliet
- Physics of Interfaces and Nanomaterials, MESA+Institute for Nanotechnology, University of Twente, 7522 NH, Enschede, The Netherlands
| | | | - Christoph Tegenkamp
- Institut für Physik, Technische Universität Chemnitz, 09126, Chemnitz, Germany.
- Institut für Festkörperphysik, Leibniz Universität Hannover, 30167, Hannover, Germany.
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43
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Tsuji Y, Yoshizawa K. Effects of electron-phonon coupling on quantum interference in polyenes. J Chem Phys 2018; 149:134115. [DOI: 10.1063/1.5048955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yuta Tsuji
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
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44
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Ortega A, Stegmann T, Benet L. Robustness of optimal transport in disordered interacting many-body networks. Phys Rev E 2018; 98:012141. [PMID: 30110776 DOI: 10.1103/physreve.98.012141] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Indexed: 11/07/2022]
Abstract
The robustness of quantum transport under various perturbations is analyzed in disordered interacting many-body systems, which are constructed from the embedded Gaussian random matrix ensembles (EGEs). The transport efficiency can be enhanced drastically, if centrosymmetry (csEGE) is imposed. When the csEGE is perturbed with an ordinary EGE, the transport efficiency in the optimal cases is reduced significantly, while in the suboptimal cases the changes are less pronounced. Qualitatively the same behavior is observed, when parity and centrosymmetry are broken by block perturbations. Analyzing the influence of the environment coupling, optimal transport is observed at a certain coupling strength, while too weak and too strong coupling reduce the transport. Taking into account the effects of decoherence, in the EGE the transport efficiency approaches its maximum at a finite nonzero decoherence strength (environment-assisted transport). In the csEGE the efficiency decays monotonically with the decoherence but is always larger than in the EGE.
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Affiliation(s)
- Adrian Ortega
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, México
| | - Thomas Stegmann
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, México
| | - Luis Benet
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, México.,Centro Internacional de Ciencias, 62210 Cuernavaca, México
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45
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Wang JS, Zhang ZQ, Lü JT. Coulomb-force-mediated heat transfer in the near field: Geometric effect. Phys Rev E 2018; 98:012118. [PMID: 30110761 DOI: 10.1103/physreve.98.012118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Indexed: 06/08/2023]
Abstract
It has been shown recently that the Coulomb part of electromagnetic interactions is more important than the transverse propagation waves for the near-field enhancement of heat transfer between metal objects at a distance of order nanometers. Here we present a theory focusing solely on the Coulomb potential between electrons hopping among tight-binding sites. When the relevant systems are reduced to very small geometry, for example, a single site, the enhancement is much higher compared to a collection of them packed within a distance of a few Å. We credit this to the screening effect. This result may be useful in designing metal-based metamaterials to enhance heat transfer much higher.
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Affiliation(s)
- Jian-Sheng Wang
- Department of Physics, National University of Singapore, Singapore 117551, Republic of Singapore
| | - Zu-Quan Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
| | - Jing-Tao Lü
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
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46
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Pedroza LS, Brandimarte P, Rocha AR, Fernández-Serra MV. Bias-dependent local structure of water molecules at a metallic interface. Chem Sci 2018; 9:62-69. [PMID: 29629074 PMCID: PMC5869310 DOI: 10.1039/c7sc02208e] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/03/2017] [Indexed: 11/21/2022] Open
Abstract
Understanding the local structure of water at the interfaces of metallic electrodes is a key issue in aqueous-based electrochemistry. Nevertheless a realistic simulation of such a setup is challenging, particularly when the electrodes are maintained at different potentials. To correctly compute the effect of an external bias potential applied to truly semi-infinite surfaces, we combine Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) methods. This framework allows for the out-of-equilibrium calculation of forces and dynamics, and directly correlates to the chemical potential of the electrodes, which is introduced experimentally. In this work, we apply this methodology to study the electronic properties and atomic forces of a water molecule at the interface of a gold surface. We find that the water molecule tends to align its dipole moment with the electric field, and it is either repelled or attracted to the metal depending on the sign and magnitude of the applied bias, in an asymmetric fashion.
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Affiliation(s)
- Luana S Pedroza
- ICTP South American Institute for Fundamental Research , Instituto de Física Teórica , Universidade Estadual Paulista , São Paulo SP 01140-070 , Brazil .
- Centro de Ciências Naturais e Humanas , Universidade Federal do ABC , Santo André , São Paulo , Brazil 09210-170
| | - Pedro Brandimarte
- Centro de Física de Materiales , 20018 Donostia - San Sebastián , Gipuzkoa , Spain
- Donostia International Physics Center , 20018 Donostia - San Sebastián , Gipuzkoa , Spain
| | - Alexandre Reily Rocha
- Instituto de Física Teórica , Universidade Estadual Paulista , São Paulo SP 01140-070 , Brazil
| | - M-V Fernández-Serra
- Department of Physics and Astronomy , Stony Brook University , Stony Brook , New York 11794-3800 , USA
- Institute for Advanced Computational Sciences , Stony Brook University , Stony Brook , New York 11794-3800 , USA
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47
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Hagenmüller D, Schachenmayer J, Schütz S, Genes C, Pupillo G. Cavity-Enhanced Transport of Charge. PHYSICAL REVIEW LETTERS 2017; 119:223601. [PMID: 29286774 DOI: 10.1103/physrevlett.119.223601] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Indexed: 05/22/2023]
Abstract
We theoretically investigate charge transport through electronic bands of a mesoscopic one-dimensional system, where interband transitions are coupled to a confined cavity mode, initially prepared close to its vacuum. This coupling leads to light-matter hybridization where the dressed fermionic bands interact via absorption and emission of dressed cavity photons. Using a self-consistent nonequilibrium Green's function method, we compute electronic transmissions and cavity photon spectra and demonstrate how light-matter coupling can lead to an enhancement of charge conductivity in the steady state. We find that depending on cavity loss rate, electronic bandwidth, and coupling strength, the dynamics involves either an individual or a collective response of Bloch states, and we explain how this affects the current enhancement. We show that the charge conductivity enhancement can reach orders of magnitudes under experimentally relevant conditions.
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Affiliation(s)
- David Hagenmüller
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
| | - Johannes Schachenmayer
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
| | - Stefan Schütz
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
| | - Claudiu Genes
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
- Max Planck Institute for the Science of Light, Staudtstraße 2, D-91058 Erlangen, Germany
| | - Guido Pupillo
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
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48
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Hahn T, Ludwig T, Timm C, Kortus J. Electronic structure, transport, and collective effects in molecular layered systems. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:2094-2105. [PMID: 29090111 PMCID: PMC5647717 DOI: 10.3762/bjnano.8.209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
The great potential of organic heterostructures for organic device applications is exemplified by the targeted engineering of the electronic properties of phthalocyanine-based systems. The transport properties of two different phthalocyanine systems, a pure copper phthalocyanine (CoPc) and a flourinated copper phthalocyanine-manganese phthalocyanine (F16CoPc/MnPc) heterostructure, are investigated by means of density functional theory (DFT) and the non-equilibrium Green's function (NEGF) approach. Furthermore, a master-equation-based approach is used to include electronic correlations beyond the mean-field-type approximation of DFT. We describe the essential theoretical tools to obtain the parameters needed for the master equation from DFT results. Finally, an interacting molecular monolayer is considered within a master-equation approach.
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Affiliation(s)
- Torsten Hahn
- Institute of Theoretical Physics, TU Freiberg, Leipziger Str. 23, D-09599 Freiberg, Germany
| | - Tim Ludwig
- Institute of Theoretical Physics, Technische Universität Dresden, 01062 Dresden, Germany
| | - Carsten Timm
- Institute of Theoretical Physics, Technische Universität Dresden, 01062 Dresden, Germany
| | - Jens Kortus
- Institute of Theoretical Physics, TU Freiberg, Leipziger Str. 23, D-09599 Freiberg, Germany
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49
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Feliciano GT, Sanz-Navarro C, Coutinho-Neto MD, Ordejón P, Scheicher RH, Rocha AR. Addressing the Environment Electrostatic Effect on Ballistic Electron Transport in Large Systems: A QM/MM-NEGF Approach. J Phys Chem B 2017; 122:485-492. [DOI: 10.1021/acs.jpcb.7b03475] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gustavo T. Feliciano
- Instituto
de Química, Departamento de Fisico-Química, Universidade Estadual Paulista (UNESP), 14800-060, Araraquara, SP, Brazil
| | - Carlos Sanz-Navarro
- Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | | | - Pablo Ordejón
- Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Ralph H. Scheicher
- Division
of Materials Theory, Department of Physics and Astronomy, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Alexandre Reily Rocha
- Instituto
de Fı́sica Teorica, Universidade Estadual Paulista (UNESP), 01140-070, São Paulo, SP, Brazil
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Hjorth Larsen A, Jørgen Mortensen J, Blomqvist J, Castelli IE, Christensen R, Dułak M, Friis J, Groves MN, Hammer B, Hargus C, Hermes ED, Jennings PC, Bjerre Jensen P, Kermode J, Kitchin JR, Leonhard Kolsbjerg E, Kubal J, Kaasbjerg K, Lysgaard S, Bergmann Maronsson J, Maxson T, Olsen T, Pastewka L, Peterson A, Rostgaard C, Schiøtz J, Schütt O, Strange M, Thygesen KS, Vegge T, Vilhelmsen L, Walter M, Zeng Z, Jacobsen KW. The atomic simulation environment-a Python library for working with atoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:273002. [PMID: 28323250 DOI: 10.1088/1361-648x/aa680e] [Citation(s) in RCA: 1038] [Impact Index Per Article: 148.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The atomic simulation environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make it possible to perform very complex simulation tasks. For example, a sequence of calculations may be performed with the use of a simple 'for-loop' construction. Calculations of energy, forces, stresses and other quantities are performed through interfaces to many external electronic structure codes or force fields using a uniform interface. On top of this calculator interface, ASE provides modules for performing many standard simulation tasks such as structure optimization, molecular dynamics, handling of constraints and performing nudged elastic band calculations.
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Affiliation(s)
- Ask Hjorth Larsen
- Nano-bio Spectroscopy Group and ETSF Scientific Development Centre, Universidad del País Vasco UPV/EHU, San Sebastián, Spain. Dept. de Ciència de Materials i Química Física & IQTCUB, Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
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