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Ugwumadu C, Thapa R, Nepal K, Gautam A, Al-Majali Y, Trembly J, Drabold DA. Self-Assembly and the Properties of Micro-Mesoporous Carbon. J Chem Theory Comput 2024; 20:1753-1762. [PMID: 37326598 DOI: 10.1021/acs.jctc.3c00394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
This study introduces a new approach for constructing atomistic models of nanoporous carbon by randomly distributing carbon atoms and pore volumes in a periodic box and then using empirical and ab initio molecular simulation tools to find the suitable energy-minimum structures. The models, consisting of 5000, 8000, 12000, and 64000 atoms, each at mass densities of 0.5, 0.75, and 1 g/cm3, were analyzed to determine their structural characteristics and relaxed pore size distribution. Surface analysis of the pore region revealed that sp atoms exist predominantly on surfaces and act as active sites for oxygen adsorption. We also investigated the electronic and vibrational properties of the models, and localized states near the Fermi level were found to be primarily situated at sp carbon atoms through which electrical conduction may occur. Additionally, the thermal conductivity was calculated using heat flux correlations and the Green-Kubo formula, and its dependence on pore geometry and connectivity was analyzed. The behavior of the mechanical elasticity moduli (Shear, Bulk, and Young's moduli) of nanoporous carbons at the densities of interest was discussed.
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Affiliation(s)
- C Ugwumadu
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, United States
| | - R Thapa
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, United States
| | - K Nepal
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, United States
| | - A Gautam
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, United States
| | - Y Al-Majali
- Department of Mechanical Engineering, Institute for Sustainable Energy and the Environment (ISEE), Ohio University, Athens, Ohio 45701, United States
| | - J Trembly
- Department of Mechanical Engineering, Institute for Sustainable Energy and the Environment (ISEE), Ohio University, Athens, Ohio 45701, United States
| | - D A Drabold
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, United States
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2
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Thapa R, Ugwumadu C, Nepal K, Trembly J, Drabold DA. Ab Initio Simulation of Amorphous Graphite. Phys Rev Lett 2022; 128:236402. [PMID: 35749197 DOI: 10.1103/physrevlett.128.236402] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/06/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
An amorphous graphite material has been predicted from molecular dynamics simulation using ab initio methods. Carbon materials reveal a strong proclivity to convert into a sp^{2} network and then layer at temperatures near 3000 K within a density range of ca. 2.2-2.8 g/cm^{3}. Each layer of amorphous graphite is a monolayer of amorphous graphene including pentagons and heptagons in addition to hexagons, and the planes are separated by about 3.1 Å. The layering transition has been studied using various structural and dynamical analyses. The transition is unique as one of partial ordering (long range order of planes and galleries, but topological disorder in the planes). The planes are quite flat, even though monolayer amorphous graphene puckers near pentagonal sites. Interplane cohesion is due partly to non-Van der Waals interactions. The structural disorder has been studied closely, especially the consequences of disorder to electronic transport. It is expected that the transition elucidated here may be salient to other layered materials.
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Affiliation(s)
- R Thapa
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, USA
| | - C Ugwumadu
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, USA
| | - K Nepal
- Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute (NQPI), Ohio University, Athens, Ohio 45701, USA
| | - J Trembly
- Department of Mechanical Engineering, Institute for Sustainable Energy and the Environment, Ohio University, Athens, Ohio 45701, USA
| | - D A Drabold
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
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Prasai K, Jiang J, Mishkin A, Shyam B, Angelova S, Birney R, Drabold DA, Fazio M, Gustafson EK, Harry G, Hoback S, Hough J, Lévesque C, MacLaren I, Markosyan A, Martin IW, Menoni CS, Murray PG, Penn S, Reid S, Robie R, Rowan S, Schiettekatte F, Shink R, Turner A, Vajente G, Cheng HP, Fejer MM, Mehta A, Bassiri R. High Precision Detection of Change in Intermediate Range Order of Amorphous Zirconia-Doped Tantala Thin Films Due to Annealing. Phys Rev Lett 2019; 123:045501. [PMID: 31491265 DOI: 10.1103/physrevlett.123.045501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Indexed: 06/10/2023]
Abstract
Understanding the local atomic order in amorphous thin film coatings and how it relates to macroscopic performance factors, such as mechanical loss, provides an important path towards enabling the accelerated discovery and development of improved coatings. High precision x-ray scattering measurements of thin films of amorphous zirconia-doped tantala (ZrO_{2}-Ta_{2}O_{5}) show systematic changes in intermediate range order (IRO) as a function of postdeposition heat treatment (annealing). Atomic modeling captures and explains these changes, and shows that the material has building blocks of metal-centered polyhedra and the effect of annealing is to alter the connections between the polyhedra. The observed changes in IRO are associated with a shift in the ratio of corner-sharing to edge-sharing polyhedra. These changes correlate with changes in mechanical loss upon annealing, and suggest that the mechanical loss can be reduced by developing a material with a designed ratio of corner-sharing to edge-sharing polyhedra.
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Affiliation(s)
- K Prasai
- E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
| | - J Jiang
- Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA
| | - A Mishkin
- Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA
| | - B Shyam
- University of Dayton Research Institute, Dayton, Ohio 45469, USA
| | - S Angelova
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Glasgow G1 1QE, United Kingdom
| | - R Birney
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Glasgow G1 1QE, United Kingdom
| | - D A Drabold
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
| | - M Fazio
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - E K Gustafson
- LIGO Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - G Harry
- Department of Physics, American University, Washington, DC 20016, USA
| | - S Hoback
- Department of Physics, American University, Washington, DC 20016, USA
| | - J Hough
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - C Lévesque
- Department of Physics, Université de Montréal, Québec H3T 1J4, Canada
| | - I MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - A Markosyan
- E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
| | - I W Martin
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - C S Menoni
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - P G Murray
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S Penn
- Department of Physics, Hobart and William Smith Colleges, Geneva, New York 14456, USA
| | - S Reid
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Glasgow G1 1QE, United Kingdom
| | - R Robie
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S Rowan
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - F Schiettekatte
- Department of Physics, Université de Montréal, Québec H3T 1J4, Canada
| | - R Shink
- Department of Physics, Université de Montréal, Québec H3T 1J4, Canada
| | - A Turner
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - G Vajente
- LIGO Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - H-P Cheng
- Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA
| | - M M Fejer
- E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
| | - A Mehta
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R Bassiri
- E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
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Abstract
In this paper, we provide evidence that low density nano-porous amorphous carbon (a-C) consists of interconnected regions of amorphous graphene (a-G). We include experimental information in producing models, while retaining the power and accuracy of ab initio methods with no biasing assumptions. Our models are highly disordered with predominant sp2 bonding and ring connectivity mainly of sizes 5-8. The structural, dynamical and electronic signatures of our 3-D amorphous graphene are similar to those of monolayer amorphous graphene. We predict an extended x-ray absorption fine structure (EXAFS) signature of amorphous graphene. Electronic density of states calculations for 3-D amorphous graphene reveal similarity to monolayer amorphous graphene and the system is non conducting.
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Affiliation(s)
- Bishal Bhattarai
- Department of Physics and Astronomy, Condensed Matter and Surface Science Program (CMSS), Ohio University, Athens, Ohio 45701, USA
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Abstract
The general and practical inversion of diffraction data-producing a computer model correctly representing the material explored-is an important unsolved problem for disordered materials. Such modeling should proceed by using our full knowledge base, both from experiment and theory. In this paper, we describe a robust method to jointly exploit the power of ab initio atomistic simulation along with the information carried by diffraction data. The method is applied to two very different systems: amorphous silicon and two compositions of a solid electrolyte memory material silver-doped GeSe3. The technique is easy to implement, is faster and yields results much improved over conventional simulation methods for the materials explored. By direct calculation, we show that the method works for both poor and excellent glass forming materials. It offers a means to add a priori information in first-principles modeling of materials, and represents a significant step toward the computational design of non-crystalline materials using accurate interatomic interactions and experimental information.
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Affiliation(s)
- Anup Pandey
- Department of Physics and Astronomy, Condensed Matter Surface Science Program, Ohio University, Athens OH 45701, USA
| | - Parthapratim Biswas
- Department of Physics and Astronomy, The University of Southern Mississippi, Hattiesburg MS 39406, USA
| | - D. A. Drabold
- Department of Physics and Astronomy, Ohio University, Athens OH 45701, USA
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6
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Abstract
Materials with optimized band gap are needed in many specialized applications. In this work, we demonstrate that Hellmann-Feynman forces associated with the gap states can be used to find atomic coordinates that yield desired electronic density of states. Using tight-binding models, we show that this approach may be used to arrive at electronically designed models of amorphous silicon and carbon. We provide a simple recipe to include a priori electronic information in the formation of computer models of materials, and prove that this information may have profound structural consequences. The models are validated with plane-wave density functional calculations.
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Affiliation(s)
- Kiran Prasai
- Department of Physics and Astronomy, Clippinger Laboratories Ohio University, Athens, OH 45701
| | - Parthapratim Biswas
- Department of Physics and Astronomy, The University of Southern Mississippi, Hattiesburg, MS 39406
| | - D A Drabold
- Department of Physics and Astronomy, Clippinger Laboratories Ohio University, Athens, OH 45701
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7
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Barik AR, Bapna M, Drabold DA, Adarsh KV. Ultrafast light induced unusually broad transient absorption in the sub-bandgap region of GeSe2 thin film. Sci Rep 2014; 4:3686. [PMID: 24418896 PMCID: PMC3890940 DOI: 10.1038/srep03686] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/05/2013] [Indexed: 11/30/2022] Open
Abstract
In this paper, we show for the first time that ultrafast light illumination can induce an unusually broad transient optical absorption (TA), spanning of ≈ 200 nm in the sub-bandgap region of chalcogenide GeSe2 thin films, which we interpret as being a manifestation of creation and annihilation of light induced defects. Further, TA in ultrashort time scales show a maximum at longer wavelength, however blue shifts as time evolves, which provides the first direct evidence of the multiple decay mechanisms of these defects. Detailed global analysis of the kinetic data clearly demonstrates that two and three decay constants are required to quantitatively model the experimental data at ps and ns respectively.
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Affiliation(s)
- A R Barik
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023, India
| | - Mukund Bapna
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023, India
| | - D A Drabold
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701-2979, USA
| | - K V Adarsh
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023, India
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8
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Zhang M, Drabold DA. The work done by an external electromagnetic field. J Phys Condens Matter 2011; 23:085801. [PMID: 21411902 DOI: 10.1088/0953-8984/23/8/085801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ehrenfest's theorem is used to derive the rate of change of kinetic energy induced by an external field. The expression for the power is valid for any electromagnetic field in arbitrary gauge. We discuss the applicable conditions for the Mott-Davis and Moseley-Lukes form of the Kubo-Greenwood formula (KGF) for the electrical conductivity which has been implemented in ab initio codes. We show that the conventional KGF does not satisfy gauge invariance, and is suitable only for computing the ac conductivity at sufficiently high frequency and when the gradient of the carrier density is small.
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Affiliation(s)
- Mingliang Zhang
- Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA.
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9
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Zhang M, Drabold DA. Comparison of the Kubo formula, the microscopic response method, and the Greenwood formula. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:012103. [PMID: 21405730 DOI: 10.1103/physreve.83.012103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 12/06/2010] [Indexed: 05/30/2023]
Abstract
For a mechanical perturbation, the microscopic response method is equivalent to and more convenient to use than the Kubo formula. When the gradient of the carrier density is small, the current density reduces to that used by Greenwood.
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Affiliation(s)
- Mingliang Zhang
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
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10
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Zhang ML, Drabold DA. Alternative approach to computing transport coefficients: application to conductivity and Hall coefficient of hydrogenated amorphous silicon. Phys Rev Lett 2010; 105:186602. [PMID: 21231124 DOI: 10.1103/physrevlett.105.186602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Indexed: 05/30/2023]
Abstract
We introduce a theoretical framework for computing transport coefficients for complex materials with extended states, and defect or band-tail states originating from static topological disorder. As a first example, we resolve long-standing inconsistencies between experiment and theory pertaining to the conductivity and Hall mobility for amorphous silicon and show that the Hall sign anomaly is a consequence of localized states. Next, we compute the ac conductivity of amorphous polyaniline. The method may be readily integrated with current ab initio methods.
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Affiliation(s)
- Ming-Liang Zhang
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
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11
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Cliffe MJ, Dove MT, Drabold DA, Goodwin AL. Structure determination of disordered materials from diffraction data. Phys Rev Lett 2010; 104:125501. [PMID: 20366543 DOI: 10.1103/physrevlett.104.125501] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/13/2010] [Indexed: 05/13/2023]
Abstract
We show that the information gained in spectroscopic experiments regarding the number and distribution of atomic environments can be used as a valuable constraint in the refinement of the atomic-scale structures of nanostructured or amorphous materials from pair distribution function (PDF) data. We illustrate the effectiveness of this approach for three paradigmatic disordered systems: molecular C60, a-Si, and a-SiO2. Much improved atomistic models are attained in each case without any a priori assumptions regarding coordination number or local geometry. We propose that this approach may form the basis for a generalized methodology for structure "solution" from PDF data applicable to network, nanostructured and molecular systems alike.
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Affiliation(s)
- Matthew J Cliffe
- Department of Earth Sciences, Cambridge University, Downing Street, Cambridge CB2 3EQ, United Kingdom
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12
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Abstract
In this paper, we review a host of methods used to model amorphous materials. We particularly describe methods which impose constraints on the models to ensure that the final model meets a priori requirements (on structure, topology, chemical order, etc). In particular, we review work based on quench from the melt simulations, the 'decorate and relax' method, which is shown to be a reliable scheme for forming models of certain binary glasses. A 'building block' approach is also suggested and yields a pleading model for GeSe(1.5). We also report on the nature of vulcanization in an Se network cross-linked by As, and indicate how introducing H into an a-Si network develops into a-Si:H. We also discuss explicitly constrained methods including reverse Monte Carlo (RMC) and a novel method called 'Experimentally Constrained Molecular Relaxation'. The latter merges the power of ab initio simulation with the ability to impose external information associated with RMC.
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Affiliation(s)
- Parthapratim Biswas
- Department of Physics and Astronomy, University of Southern Mississippi, Hattiesburg, MS 39406, USA
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13
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Abstract
Exponential band edges have been observed in a variety of materials, both crystalline and amorphous. In this Letter, we infer the structural origins of these tails in amorphous and defective crystalline Si by direct calculation with current ab initio methods. We find that exponential tails appear in relaxed models of diamond silicon with suitable extended defects that emerge from relaxing point defects. In amorphous silicon (a-Si), we find that structural filaments of short bonds and long bonds exist in the network, and that the tail states near the extreme edges of both band tails are also filamentary, with much localization on the structural filaments. We connect the existence of both filament systems to structural relaxation in the presence of defects and of topological disorder.
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Affiliation(s)
- Y Pan
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
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14
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Bandyopadhyay K, Bhattacharya AK, Biswas P, Drabold DA. Maximum entropy and the problem of moments: a stable algorithm. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 71:057701. [PMID: 16089706 DOI: 10.1103/physreve.71.057701] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Indexed: 05/03/2023]
Abstract
We present a technique for entropy optimization to calculate a distribution from its moments. The technique is based upon maximizing a discretized form of the Shannon entropy functional by mapping the problem onto a dual space where an optimal solution can be constructed iteratively. We demonstrate the performance and stability of our algorithm with several tests on numerically difficult functions. We then consider an electronic structure application, the electronic density of states of amorphous silica, and study the convergence of the Fermi level with increasing number of moments.
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Affiliation(s)
- K Bandyopadhyay
- Department of Physics, University of Burdwan, Burdwan, West Bengal 713104, India
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15
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Taraskin SN, Drabold DA, Elliott SR. Spatial decay of the single-particle density matrix in insulators: analytic results in two and three dimensions. Phys Rev Lett 2002; 88:196405. [PMID: 12005655 DOI: 10.1103/physrevlett.88.196405] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2001] [Indexed: 05/23/2023]
Abstract
Analytic results for the asymptotic decay of the electron density matrix in insulators have been obtained in all three dimensions (D = 1,2,3) for a tight-binding model defined on a simple cubic lattice. The anisotropic decay length is shown to be dependent on the energy parameters of the model. The existence of the power-law prefactor, proportional, variant r(-D/2), is demonstrated.
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Affiliation(s)
- S N Taraskin
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
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16
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Li J, Drabold DA, Krishnaswami S, Chen G, Jain H. Electronic structure of glassy chalcogenides As4Se4 and As2Se3: a joint theoretical and experimental study. Phys Rev Lett 2002; 88:046803. [PMID: 11801151 DOI: 10.1103/physrevlett.88.046803] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2001] [Indexed: 05/23/2023]
Abstract
We present an interpretation of the x-ray absorption spectra of arsenic chalcogenide glasses, As4Se4 and As2Se3, from a first-principles calculation. Our calculation identifies the atomistic origins of the observed photoemission data. The importance of structural "building blocks" present in a particular glass to the electron states is emphasized. The effects of disorder on the electronic spectra are clearly demonstrated by a significant change in the electronic density of states, originating in the breakdown of long-range order coherence in the bonding states of the building blocks. We discuss the relation between observed in situ light-induced changes and the electronic structure.
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Affiliation(s)
- Jun Li
- Department of Physics and Astronomy, Condensed Matter and Surface Science Program, Ohio University, Athens, Ohio 45701-2979, USA
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17
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Li J, Drabold DA. Direct calculation of light-induced structural change and diffusive motion in glassy As2Se3. Phys Rev Lett 2000; 85:2785-2788. [PMID: 10991233 DOI: 10.1103/physrevlett.85.2785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2000] [Indexed: 05/23/2023]
Abstract
Photostructural change of glassy As2Se3 was simulated on an experimentally credible model with excited electronic dynamics within first-principles molecular dynamics. Bond breaking and bond switching reactions account for local changes around defect sites at the short time phase of illumination. For long-time relaxation, defect pairs associated with band tail states become involved in a rearrangement in the network, giving rise to a low energy, nonlocal "polaronlike" collective oscillation. Diffusive motion is observed for short times, which we tentatively interpret as the initial phase of athermal photomelting.
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Affiliation(s)
- J Li
- Department of Physics and Astronomy, Condensed Matter and Surface Science Program, Ohio University, Athens, Ohio 45701, USA
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18
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Abstract
We illustrate the structure and dynamics of electron states in amorphous Si. The nature of the states near the gap at zero temperature is discussed and especially the way the structure of the states changes for energies ranging from midgap into either band tail (Anderson transition). We then study the effect of lattice vibrations on the eigenstates, and find that electronic states near the optical gap can be strongly influenced by thermal modulation of the atomic positions. Finally, we show the structure of generalized Wannier functions for amorphous Si, which are of particular interest for efficient ab initio calculation of electronic properties and forces for first principles dynamic simulation.
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Affiliation(s)
- D A Drabold
- Department of Physics and Astronomy, Ohio University, Athens 45701-2979, USA.
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19
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Cobb M, Drabold DA, Cappelletti RL. Ab initio molecular-dynamics study of the structural, vibrational, and electronic properties of glassy GeSe2. Phys Rev B Condens Matter 1996; 54:12162-12171. [PMID: 9985075 DOI: 10.1103/physrevb.54.12162] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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20
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Dong J, Drabold DA. Band-tail states and the localized-to-extended transition in amorphous diamond. Phys Rev B Condens Matter 1996; 54:10284-10287. [PMID: 9984804 DOI: 10.1103/physrevb.54.10284] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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21
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Alfonso DR, Noguez C, Drabold DA, Ulloa SE. First-principles studies of hydrogenated Si(111)-7 x 7. Phys Rev B Condens Matter 1996; 54:8028-8032. [PMID: 9984480 DOI: 10.1103/physrevb.54.8028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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22
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Drabold DA, Fedders PA, Grumbach MP. Gap formation and defect states in tetrahedral amorphous carbon. Phys Rev B Condens Matter 1996; 54:5480-5484. [PMID: 9986508 DOI: 10.1103/physrevb.54.5480] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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23
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Song J, Ulloa SE, Drabold DA. Exciton-induced lattice relaxation and the electronic and vibrational spectra of silicon clusters. Phys Rev B Condens Matter 1996; 53:8042-8051. [PMID: 9982262 DOI: 10.1103/physrevb.53.8042] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Fedders PA, Drabold DA. Molecular-dynamics investigations of conformational fluctuations and low-energy vibrational excitations in a-Si:H. Phys Rev B Condens Matter 1996; 53:3841-3845. [PMID: 9983936 DOI: 10.1103/physrevb.53.3841] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Itoh S, Ordejón P, Drabold DA, Martin RM. Structure and energetics of giant fullerenes: An order-N molecular-dynamics study. Phys Rev B Condens Matter 1996; 53:2132-2140. [PMID: 9983678 DOI: 10.1103/physrevb.53.2132] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Cappelletti RL, Cobb M, Drabold DA, Kamitakahara WA. Neutron-scattering and ab initio molecular-dynamics study of vibrations in glassy GeSe2. Phys Rev B Condens Matter 1995; 52:9133-9136. [PMID: 9979942 DOI: 10.1103/physrevb.52.9133] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ordejón P, Drabold DA, Martin RM, Itoh S. Linear scaling method for phonon calculations from electronic structure. Phys Rev Lett 1995; 75:1324-1327. [PMID: 10060264 DOI: 10.1103/physrevlett.75.1324] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Alfonso DR, Drabold DA, Ulloa SE. Structural, electronic, and vibrational properties of diamond (100), (111), and (110) surfaces from ab initio calculations. Phys Rev B Condens Matter 1995; 51:14669-14685. [PMID: 9978402 DOI: 10.1103/physrevb.51.14669] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ordejón P, Drabold DA, Martin RM, Grumbach MP. Linear system-size scaling methods for electronic-structure calculations. Phys Rev B Condens Matter 1995; 51:1456-1476. [PMID: 9978860 DOI: 10.1103/physrevb.51.1456] [Citation(s) in RCA: 142] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Alfonso DR, Drabold DA, Ulloa SE. Phonon modes of diamond (100) surfaces from ab initio calculations. Phys Rev B Condens Matter 1995; 51:1989-1992. [PMID: 9978934 DOI: 10.1103/physrevb.51.1989] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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31
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Alfonso DR, Yang SH, Drabold DA. Ab initio studies of hydrocarbon adsorption on stepped diamond surfaces. Phys Rev B Condens Matter 1994; 50:15369-15380. [PMID: 9975889 DOI: 10.1103/physrevb.50.15369] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sankey OF, Drabold DA, Gibson A. Projected random vectors and the recursion method in the electronic-structure problem. Phys Rev B Condens Matter 1994; 50:1376-1381. [PMID: 9976322 DOI: 10.1103/physrevb.50.1376] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Drabold DA, Stumm P, Fedders PA. Comment on "Structure, dynamics, and electronic properties of diamondlike amorphous carbon". Phys Rev Lett 1994; 72:2666. [PMID: 10055943 DOI: 10.1103/physrevlett.72.2666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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35
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Caro A, Drabold DA, Sankey OF. Properties of the Al-Si solid solution: Dynamical properties of the silicon substitutional and the aluminum vacancy. Phys Rev B Condens Matter 1994; 49:6647-6654. [PMID: 10009384 DOI: 10.1103/physrevb.49.6647] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kilian KA, Drabold DA, Adams JB. First-principles simulations of a-Si and a-Si:H surfaces. Phys Rev B Condens Matter 1993; 48:17393-17399. [PMID: 10008351 DOI: 10.1103/physrevb.48.17393] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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37
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Ordejón P, Drabold DA, Grumbach MP, Martin RM. Unconstrained minimization approach for electronic computations that scales linearly with system size. Phys Rev B Condens Matter 1993; 48:14646-14649. [PMID: 10007888 DOI: 10.1103/physrevb.48.14646] [Citation(s) in RCA: 198] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Fedders PA, Drabold DA. Hydrogen and defects in first-principles molecular-dynamics-modeled a-Si:H. Phys Rev B Condens Matter 1993; 47:13277-13282. [PMID: 10005632 DOI: 10.1103/physrevb.47.13277] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Yang SH, Drabold DA, Adams JB, Sachdev A. First-principles local-orbital density-functional study of Al clusters. Phys Rev B Condens Matter 1993; 47:1567-1576. [PMID: 10006172 DOI: 10.1103/physrevb.47.1567] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Phillips R, Drabold DA, Lenosky T, Adams GB, Sankey OF. Electronic structure of schwarzite. Phys Rev B Condens Matter 1992; 46:1941-1943. [PMID: 10003863 DOI: 10.1103/physrevb.46.1941] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
First-principles calculations were performed to compare the energies of 29 different fullerene structures, with mass number from 60 to 240, and of eight nonhelical graphite tubes of different radii. A quantity called the planarity, which indicates the completeness of the pi-bonding, is the single most important parameter determining the energetics of these structures. Empirical equations were constructed for the energies of nonhelical tubes and for those fullerene structures that may be described as balls or capsules. For a given mass number, bail-shaped fullerenes are energetically favored over capsular (tube-like) fullerenes.
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Fedders PA, Drabold DA, Klemm S. Defects, tight binding, and first-principles molecular-dynamics simulations on a-Si. Phys Rev B Condens Matter 1992; 45:4048-4055. [PMID: 10002017 DOI: 10.1103/physrevb.45.4048] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Drabold DA, Wang R, Klemm S, Sankey OF, Dow JD. Efficient ab initio molecular-dynamics simulations of carbon. Phys Rev B Condens Matter 1991; 43:5132-5134. [PMID: 9997891 DOI: 10.1103/physrevb.43.5132] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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48
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Drabold DA, Dow JD, Fedders PA, Carlsson AE, Sankey OF. Convergence of force calculations for noncrystalline Si. Phys Rev B Condens Matter 1990; 42:5345-5348. [PMID: 9996105 DOI: 10.1103/physrevb.42.5345] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Drabold DA, Fedders PA, Sankey OF, Dow JD. Molecular-dynamics simulations of amorphous Si. Phys Rev B Condens Matter 1990; 42:5135-5141. [PMID: 9996075 DOI: 10.1103/physrevb.42.5135] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sankey OF, Niklewski DJ, Drabold DA, Dow JD. Molecular-dynamics determination of electronic and vibrational spectra, and equilibrium structures of small Si clusters. Phys Rev B Condens Matter 1990; 41:12750-12759. [PMID: 9993752 DOI: 10.1103/physrevb.41.12750] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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