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Mandal P, Panda AN. Contrasting the excited state properties of different conformers of trans- and cis-2,2'-bipyridine oligomers in the gas phase. Phys Chem Chem Phys 2024; 26:2646-2656. [PMID: 38174437 DOI: 10.1039/d3cp05313j] [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: 01/05/2024]
Abstract
In this article, we present conformation-dependent photophysical and excited state properties of trans- and cis- BPY oligomers. Oligomers up to tetramers for three conformers, namely, o-, m-, and p-, are constructed and optimized at the B3LYP-D3/def2-SVPD level. The photophysical and excited state properties are interpreted in terms of UV and CD spectra at the RI-ADC(2)/def2-TZVPD level. The UV spectra of oligomers of the m-conformer show high-intensity and red-shifted UV bands compared to o- and p-oligomers. The CD spectra of p-oligomers show intense CD bands compared to o- and p-oligomers in the case of trans-structures. In contrast, oligomers of each conformer of cis-structures show high-intensity CD bands. The excited states of (BPY)2 and (BPY)4 are also characterized by analysis of one-electron transition density matrix considering three descriptors: ωCT, dexc, and PRNTO. The ωCT values of dimers are in the range of 0.06-0.32, which indicates the excited states are mainly LE states, whereas, for (BPY)4, the ωCT values range from 0.17 to 0.53, indicating the possibility of partial CT in the excited states. These observations are also explained using the NTOs and e-h correlation plots.
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Affiliation(s)
- Palak Mandal
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India.
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India.
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2
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Mandal P, Panda AN. Conformational Effect on the Excitonic States of 2-Phenylpyridine Oligomers: Ab Initio Studies and Analysis. J Phys Chem A 2023; 127:7898-7907. [PMID: 37703054 DOI: 10.1021/acs.jpca.3c03601] [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: 09/14/2023]
Abstract
In this work, we report the effect of different conformations of 2-phenylpyridine oligomers ((PhPy)n=1-5) on the excited state properties from the results obtained at the RI-ADC(2)/def2-TZVP level. Three different conformers, namely, A, B, and C, are considered for each oligomer. All the oligomers of conformer A have linear-type structures, whereas conformers B and C form helical structures at n = 5 and n = 3, respectively. The differences in the geometries of the three conformers are reflected in the UV and CD spectra. The UV spectra of conformer A show high-intensity peaks compared to the conformers B and C, for each oligomer. While the helical oligomers of conformers B and C show high-intensity CD bands, the intensities of CD bands for all of the oligomers of conformer A are weaker. Analysis of the properties of the first five excited states in (PhPy)5 is carried out using three descriptors, and the results reveal that these are partially charge transfer states.
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Affiliation(s)
- Palak Mandal
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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3
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Mawa I, Panda AN. Theoretical Investigation of the E/ Z Photoisomerization Pathway in 1-(2-Pyrrolyl)-2-(2-thienyl)ethylene. J Phys Chem A 2023. [PMID: 37395607 DOI: 10.1021/acs.jpca.3c02184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Molecular-level understanding of photochemistry in simple vinylene-linked systems such as ethylene and stilbene has been a major area of research. However, the effect of replacing the two benzene rings by five-membered heterocyclic rings, thiophene and pyrrole, is yet to be reported. In the present theoretical study, our aim is to illustrate photoinduced processes in a vinylene-linked thiophene-pyrrole system. Computational studies are carried out at the RI-MP2/RI-ADC(2)/cc-pVTZ level to explore different isomerization pathways. Minimum-energy conical intersection (MECI) structures are categorized into two types: closed-ring and twisted-pyramidalized structures. Relaxation through the former MECIs is accessible only from the cis isomers. However, the latter MECIs are inaccessible due to high energy barriers along the linear interpolation in internal coordinate paths.
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Affiliation(s)
- Ibanrishisha Mawa
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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4
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Saharia A, Mahato B, Mishra BK, Panda AN. Effect of Fluorine Substitution on Absorption and Emission Properties of Figure-eight-shaped [5]Helicene Dimer : A Computational Study at RI-MP2/RI-ADC(2) Level. Chemphyschem 2023:e202300006. [PMID: 36988003 DOI: 10.1002/cphc.202300006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 03/30/2023]
Abstract
Chirality is a very important characteristic of optically active molecules and polyaromatics with helical structures, and plays a vital role in various applications in material science. In the present work, we show the effects of fluorine substitution at various positions in a figure-8-shaped [5]helicene dimer on the ground and excited state $g$-factors. Calculations for the ground and excited states are performed at the MP2 and ADC(2) levels of theory, respectively. The results reveal that fluorination has a large effect on the excited state structures. The values of the excited state dissymmetry factors for the molecules with fluorinations at both ends of the figure-8 systems are smaller than that of the parent system. On the other hand, fluorinations only in the stacked-phenyl region results in an increase in the value of |gcpl|. The perfluorinated system shows the smallest |gcpl|.
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Affiliation(s)
- Abhishek Saharia
- IIT Guwahati: Indian Institute of Technology Guwahati, Chemistry, INDIA
| | - Bishwanath Mahato
- IIT Guwahati: Indian Institute of Technology Guwahati, Chemistry, INDIA
| | | | - Aditya N Panda
- IIT Guwahati, Chemistry, IIT Guwahati, 781039, Guwahati, INDIA
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5
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Mahato B, Panda AN. Effect of Terminal Fluorination on Chiroptical Properties of Carbo[5-8]helicenes: A Systematic Computational Study at the RI-ADC(2) Level. J Phys Chem A 2023; 127:2284-2294. [PMID: 36882992 DOI: 10.1021/acs.jpca.2c08474] [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: 03/09/2023]
Abstract
In this article, effects of di-, tetra-, and octafluorination on the structural and chiroptical properties of carbo[5-8]helicenes are reported. Three fluorinated derivatives are designed from each parent carbohelicene by substituting either one, two, or four hydrogens at each terminal ring with fluorine atoms. Excited states properties such as UV-vis and CD spectra of all the six fluorinated carbohelicenes are computed at the ADC(2)/def2-TZVP level, and the results are compared against the results of their respective parent carbohelicene. In addition, CPL properties are also computed at the same level of theory. In the case of carbo[5]helicene (5H), gCPL decreases with an increase in the degree of fluorination. A similar observation is made in carbo[6]helicene (6H) too, although the value for tetrafluorinated 6H is slightly larger than for difluorinated 6H. Di- and tetrafluorination in carbo[7]helicene (7H), and all types of considered fluorination in carbo[8]helicene (8H) produce improved gCPL results. Results for fluorescence rate constants are also shown. Results are analyzed in terms of the transition dipole moment vectors and the angles between those.
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Affiliation(s)
- Bishwanath Mahato
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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Mawa I, Panda AN. Excited state processes in nitrile-substituted 2-(oxazolinyl)-phenols in gas and implicit solvents: A computational study. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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7
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Saroj A, Venkatnarayan R, Mishra BK, Panda AN, Narayanasami S. Improved Estimates of Host‐Guest Interaction Energies for Endohedral Fullerenes Containing Rare Gas Atoms, Small Molecules, and Cations. Chemphyschem 2022; 23:e202200413. [DOI: 10.1002/cphc.202200413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/18/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Arti Saroj
- IIT BHU: Indian Institute of Technology BHU Varanasi Chemistry 221005 Varanasi INDIA
| | | | | | - Aditya N. Panda
- IIT Guwahati: Indian Institute of Technology Guwahati Chemistry 781039 INDIA
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Mahato B, Panda AN. Effects of Heterocyclic Ring Fusion and Chain Elongation on Chiroptical Properties of Polyaza[9]helicene: A Computational Study. J Phys Chem A 2022; 126:1412-1421. [PMID: 35192355 DOI: 10.1021/acs.jpca.2c00432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the present work, the effect of lateral and helical extensions on the physical and chiroptical properties of azahelicenes is reported. Starting with the experimentally reported polyaza[9]helicene (9Ha), three derivatives, two with laterally fused electron-withdrawing rings and the third with larger helical length, are designed. For the excited-state properties such as UV-vis and CD spectra, performances of different DFT functionals are evaluated by comparing the energies and characters of the excited states against the ADC(2) results. CPL properties are calculated at DFT level. Among the three designed systems, pyrazine-based 9HaP shows an improved gCPL value compared to that for parent 9Ha. However, quinoxaline-based 9HaQ is found to be the worst CPL emitter with the lowest dissymmetry factor. The helically extended derivative, 11Ha, shows good CPL results, but gCPL remains smaller than that for the parent system. The CPL results are analyzed in terms of electric dipole transition moment (EDTM) and magnetic dipole transition moment (MDTM) vectors, and angles between these two vectors.
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Affiliation(s)
- Bishwanath Mahato
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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Kesari S, Mishra BK, Panda AN. Excited states in RED/near infrared region TADF molecules: TDDFT vs ADC(2). Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Shavez M, Panda AN. Assessing Effects of Different π bridges on Properties of Random Benzodithiophene-thienothiophene Donor and Non-fullerene Acceptor Based Active Layer. J Phys Chem A 2021; 125:9852-9864. [PMID: 34738461 DOI: 10.1021/acs.jpca.1c07378] [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: 11/28/2022]
Abstract
This report presents the effect of insertion of four different π bridges, furan, thienothiophene, thiophene, and thiazole, into a random benzodithiophene (BDT)-fluorinated-thienothiophene (TT-F) based donor. Starting from a structure of synthesized donor (D)-acceptor (A) random copolymer with 3:1 ratio, we have designed four D-π-A systems with four different π bridges. Structural, optoelectronic, and charge transport/transfer properties of these donors and donor/NDI (NDI = poly[N,N'-bis(2-hexyldecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)) blends are investigated using DFT and TD-DFT methodologies. Our results show that the thiazole based TzP1 oligomer has the deepest HOMO value resulting in the highest open circuit voltage among all systems. The maximum absorption wavelengths of π-linked systems are red-shifted compared to the parent molecule. Rates of charge transfer and charge recombination are the highest and smallest in case of the thiazole/NDI blend system. In addition, hole mobilities in thiophene, thienothiophene, and thiazole based systems are larger than in the parent system. The results indicate that the thiazole unit among the four π bridge units is the most suitable for active layer construction.
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Affiliation(s)
- Mohd Shavez
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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11
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Koner D, Barrios L, González-Lezana T, Panda AN. Atom-Diatom Reactive Scattering Collisions in Protonated Rare Gas Systems. Molecules 2021; 26:4206. [PMID: 34299481 PMCID: PMC8304066 DOI: 10.3390/molecules26144206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 11/17/2022] Open
Abstract
The study of the dynamics of atom-diatom reactions involving two rare gas (Rg) atoms and protons is of crucial importance given the astrophysical relevance of these processes. In a series of previous studies, we have been investigating a number of such Rg(1)+ Rg(2)H+→ Rg(2)+ Rg(1)H+ reactions by means of different numerical approaches. These investigations comprised the construction of accurate potential energy surfaces by means of ab initio calculations. In this work, we review the state-of-art of the study of these protonated Rg systems making special emphasis on the most relevant features regarding the dynamical mechanisms which govern these reactive collisions. The aim of this work therefore is to provide an as complete as possible description of the existing information regarding these processes.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Karakambadi Road, Tirupati 517507, Andhra Pradesh, India;
| | - Lizandra Barrios
- Department of Chemistry, CMS—Centre for Molecular Simulation, IQST—Institute for Quantum Science and Technology and Quantum Alberta, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada;
| | | | - Aditya N. Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India;
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12
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Shavez M, Ray AK, Panda AN. Halogenation of the Side Chains in Donor‐Acceptor Based Small Molecules for Photovoltaic Applications: Energetics and Charge‐Transfer Properties from DFT/TDDFT Studies. ChemistrySelect 2021. [DOI: 10.1002/slct.202100921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mohd Shavez
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati 781039 India
| | - Anuj Kumar Ray
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati 781039 India
| | - Aditya N. Panda
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati 781039 India
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13
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Abstract
1-Hydroxy-2-acetonaphthone (HAN) has been extensively studied both experimentally and computationally to ascertain the existence of the excited-state proton transfer process. However, the process of full photocycle including the nonradiative relaxation pathways is yet to be proposed. Therefore, in the present study, we aim at providing a comprehensive picture of the excited-state processes in HAN including the proton transfer and relaxation processes through electronic structure calculations at second-order algebraic diagrammatic construction (ADC(2)) and complete active space second-order perturbation theory (CASPT2)//complete active space self-consistent field (CASSCF) and dynamics simulations at ADC(2) levels. Our studies show that the proton transfer process in the S1 state is barrierless and produces a stable keto form, which is in accordance with previous experimental and computational studies. Adiabatic dynamics simulations at the ADC(2) level confirmed the ultrafast process with an average proton transfer time of 43 fs. The resultant keto conformer then undergoes torsional rotation, leading to a conical intersection that mediates the internal conversion process to the ground state. Our dynamics simulation predicted that this deactivation process occurs at a time scale beyond 600 fs of simulation time. We also explored nonradiative relaxation from the enol Franck-Condon region, and this process was found to be improbable from the static point of view at both the ADC(2) and CASPT2 levels of theory due to a high energy barrier along the torsional coordinate.
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Affiliation(s)
- Ibanrishisha Mawa
- Department of Chemistry, Indian Institute of Technology, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology, Guwahati 781039, India
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Abstract
In this article, we have examined the accuracy of various density functional theory (DFT) functionals to reproduce the absorption and CD spectra of pyridine-thiophene oligomers. The performance of different levels of approximations in DFT functionals is discussed with reference to the ADC(2) results. Starting from a linear system, like monomer, calculations are carried out at ADC(2) and DFT levels till a helical system, like pentamer, is formed. For vertical excitation energies, results obtained with functionals, like CAM-B3LYP, ωB97XD, and M06-2X, are closer to the ADC(2) results. However, analysis of excited-state properties shows that the state ordering patterns or results regarding natural transition orbitals from these DFT functionals sometimes differ from the ADC(2) results. Global hybrid functionals like B3LYP and PBE0 produce excitation energies which are far away from the ADC(2) benchmark results. Similarly, pure functionals and their long-range corrected versions produce either redshifted or blueshifted energies. For the CD spectra, the above three mentioned functionals, CAM-B3LYP, ωB97XD, and M06-2X, again produce spectra closer to the benchmark spectra.
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Affiliation(s)
- Bishwanath Mahato
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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Shavez M, Panda AN. Effects of π-bridge units on the properties of donor-π-acceptor type benzodithiophene-thienothiophene based polymers for organic solar cells. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137810] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Shavez M, Goswami J, Panda AN. Effect of fluorination of the donor unit on the properties of benzodithiophene-triazole based donor-acceptor systems for polymer solar cells: A computational investigation. COMPUT THEOR CHEM 2019. [DOI: 10.1016/j.comptc.2019.112564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Sahu H, Shukla R, Goswami J, Gaur P, Panda AN. Alternating phenylene and furan/pyrrole/thiophene units-based oligomers: A computational study of the structures and optoelectronic properties. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2017.12.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Koner D, Barrios L, González-Lezana T, Panda AN. Scattering study of the Ne + NeH(+)(v0 = 0, j0 = 0) → NeH(+) + Ne reaction on an ab initio based analytical potential energy surface. J Chem Phys 2016; 144:034303. [PMID: 26801030 DOI: 10.1063/1.4939952] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Initial state selected dynamics of the Ne + NeH(+)(v0 = 0, j0 = 0) → NeH(+) + Ne reaction is investigated by quantum and statistical quantum mechanical (SQM) methods on the ground electronic state. The three-body ab initio energies on a set of suitably chosen grid points have been computed at CCSD(T)/aug-cc-PVQZ level and analytically fitted. The fitting of the diatomic potentials, computed at the same level of theory, is performed by spline interpolation. A collinear [NeHNe](+) structure lying 0.72 eV below the Ne + NeH(+) asymptote is found to be the most stable geometry for this system. Energies of low lying vibrational states have been computed for this stable complex. Reaction probabilities obtained from quantum calculations exhibit dense oscillatory structures, particularly in the low energy region and these get partially washed out in the integral cross section results. SQM predictions are devoid of oscillatory structures and remain close to 0.5 after the rise at the threshold thus giving a crude average description of the quantum probabilities. Statistical cross sections and rate constants are nevertheless in sufficiently good agreement with the quantum results to suggest an important role of a complex-forming dynamics for the title reaction.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Lizandra Barrios
- IFF-CSIC, Instituto de Física Fundamental, CSIC, Serrano 123, Madrid 28006, Spain
| | | | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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Koner D, Barrios L, González-Lezana T, Panda AN. State-to-State Dynamics of the Ne + HeH(+) (v = 0, j = 0) → NeH(+)(v', j') + He Reaction. J Phys Chem A 2016; 120:4731-41. [PMID: 26943458 DOI: 10.1021/acs.jpca.5b11477] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamics of the Ne + HeH(+)(v = 0, j = 0) → NeH(+)(v', j') + He reaction was analyzed in detail at the state-to-state level. A time-independent quantum mechanical (TIQM) method was applied to calculate rovibrational distributions and differential cross sections (DCSs), in comparison with quasi-classical trajectory and statistical quantum predictions. Possible changes in the dynamical mechanisms that define the process were also investigated as a function of the collision energy. At the lowest energy regime, the TIQM results produce a noticeably different cross section in comparison with previously reported time-dependent wave packet results. Although the statistical methods reproduce some dynamical features, especially as the energy increases, the marked preference for the forward scattering direction on the DCSs suggests that the reaction mainly follows a direct mechanism.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Technology , Guwahati 781039, India
| | - Lizandra Barrios
- Instituto de Física Fundamental, IFF-CSIC , Serrano 123, Madrid 28006, Spain
| | | | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology , Guwahati 781039, India
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Koner D, Barrios L, González-Lezana T, Panda AN. Quantum, Statistical, and Quasiclassical Trajectory Studies For the Ne + HeH(+) → NeH(+) + He Reaction on the Ground Electronic State. J Phys Chem A 2015; 119:12052-61. [PMID: 26172109 DOI: 10.1021/acs.jpca.5b04830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Real wave packet, statistical quantum, and quasiclassical trajectory methods were employed to study the dynamics of Ne + HeH(+)(v0,j0) → He + NeH(+) reaction on an ab initio potential energy surface [J. Phys. Chem. A 2013, 117, 13070-13078]. Quantum and statistical quantum calculations were performed within the centrifugal sudden (CS) approximation as well as including the Coriolis coupling (CC). Dense oscillatory structures of the quantum reaction probabilities and fair agreement between quantum and statistical cross sections suggest a complex forming mechanism for the reaction. No significant differences between cross sections obtained within the CS and CC approaches are observed. Quasiclassical trajectory results give an excellent average description of the quantum CC results. At low collision energies, there is a substantial decrease in reactivity for the reaction upon rovibrational excitation. Initial state selected rate constants for the title reaction are calculated between 20 and 1000 K, and the calculated value at 300 K agrees quite well with the available experimental result. Reaction cross sections and rate constants are also compared with those calculated via the Langevin capture model for exothermic reactions.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Lizandra Barrios
- Instituto de Física Fundamental, C.S.I.C. , Serrano 123, Madrid 28006, Spain
| | | | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India
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21
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Koner D, Barrios L, González-Lezana T, Panda AN. Wave packet and statistical quantum calculations for the He + NeH⁺ → HeH⁺ + Ne reaction on the ground electronic state. J Chem Phys 2015; 141:114302. [PMID: 25240353 DOI: 10.1063/1.4895567] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A real wave packet based time-dependent method and a statistical quantum method have been used to study the He + NeH(+) (v, j) reaction with the reactant in various ro-vibrational states, on a recently calculated ab initio ground state potential energy surface. Both the wave packet and statistical quantum calculations were carried out within the centrifugal sudden approximation as well as using the exact Hamiltonian. Quantum reaction probabilities exhibit dense oscillatory pattern for smaller total angular momentum values, which is a signature of resonances in a complex forming mechanism for the title reaction. Significant differences, found between exact and approximate quantum reaction cross sections, highlight the importance of inclusion of Coriolis coupling in the calculations. Statistical results are in fairly good agreement with the exact quantum results, for ground ro-vibrational states of the reactant. Vibrational excitation greatly enhances the reaction cross sections, whereas rotational excitation has relatively small effect on the reaction. The nature of the reaction cross section curves is dependent on the initial vibrational state of the reactant and is typical of a late barrier type potential energy profile.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Lizandra Barrios
- Instituto de Física Fundamental, C.S.I.C., Serrano 123, Madrid 28006, Spain
| | | | - Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
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Sahu H, Gupta S, Gaur P, Panda AN. Structure and optoelectronic properties of helical pyridine–furan, pyridine–pyrrole and pyridine–thiophene oligomers. Phys Chem Chem Phys 2015. [DOI: 10.1039/c5cp02872h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The optoelectronic properties of helical structures pyridine–furan, pyridine–pyrrole and pyridine–thiophene oligomers are explored using density functional theory methods.
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Affiliation(s)
- Harikrishna Sahu
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
| | - Shashwat Gupta
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
| | - Priyank Gaur
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
| | - Aditya N. Panda
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
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Sahu H, Panda AN. Computational investigation of charge injection and transport properties of a series of thiophene–pyrrole based oligo-azomethines. Phys Chem Chem Phys 2014; 16:8563-74. [DOI: 10.1039/c3cp55243h] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Abstract
An analytical potential energy surface (PES) for the ground state of the [HeHNe](+) system has been constructed from a set of 19,605 ab initio data points, obtained from coupled cluster singles and doubles with perturbative triples correction calculations and the aug-cc-pVQZ basis set. The PES is based on the many-body expansion form proposed by Aguado and Paniagua (J. Chem. Phys. 1992, 96, 1265), and it has a root-mean-square error of 0.03 kcal/mol. The minimum energy pathways (MEPs) for different Ne-H-He angles are calculated, and it is found that the MEP for 180° (linear) goes through the deepest potential energy well. Preliminary quantum dynamical studies are performed for the He + NeH(+) (v = 0-2, j = 0-3) → HeH(+) + Ne reaction in the 0.0-0.5 eV collision energy range. Quantum calculations are carried out using a time-dependent wave packet method within the centrifugal sudden approximation. Reaction probabilities exhibit strong oscillatory behavior arising because of the metastable [HeHNe](+). Vibrational excitation has been found to enhance the reaction cross sections.
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Affiliation(s)
- Debasish Koner
- Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781039, India
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Panda AN, Plasser F, Aquino AJA, Burghardt I, Lischka H. Electronically excited states in poly(p-phenylenevinylene): vertical excitations and torsional potentials from high-level ab initio calculations. J Phys Chem A 2013; 117:2181-9. [PMID: 23427902 PMCID: PMC3598239 DOI: 10.1021/jp400372t] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [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] [Indexed: 11/29/2022]
Abstract
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Ab
initio second-order algebraic diagrammatic construction (ADC(2)) calculations
using the resolution of the identity (RI) method have been performed
on poly-(p-phenylenevinylene) (PPV) oligomers with
chain lengths up to eight phenyl rings. Vertical excitation energies
for the four lowest π–π* excitations and geometry
relaxation effects for the lowest excited state (S1) are
reported. Extrapolation to infinite chain length shows good agreement
with analogous data derived from experiment. Analysis of the bond
length alternation (BLA) based on the optimized S1 geometry
provides conclusive evidence for the localization of the defect in
the center of the oligomer chain. Torsional potentials have been computed
for the four excited states investigated and the transition densities
divided into fragment contributions have been used to identify excitonic
interactions. The present investigation provides benchmark results,
which can be used (i) as reference for lower level methods and (ii)
give the possibility to parametrize an effective Frenkel exciton Hamiltonian
for quantum dynamical simulations of ultrafast exciton transfer dynamics
in PPV type systems.
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Affiliation(s)
- Aditya N Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
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Sahu H, Panda AN. Computational Study on the Effect of Substituents on the Structural and Electronic Properties of Thiophene–Pyrrole-Based π-Conjugated Oligomers. Macromolecules 2013. [DOI: 10.1021/ma3024409] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Harikrishna Sahu
- Department of Chemistry, Indian Institute of Technology Guwahati, India, 781039
| | - Aditya N. Panda
- Department of Chemistry, Indian Institute of Technology Guwahati, India, 781039
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Panda AN, Herráez-Aguilar D, Jambrina PG, Aldegunde J, Althorpe SC, Aoiz FJ. A state-to-state dynamical study of the Br + H2 reaction: comparison of quantum and classical trajectory results. Phys Chem Chem Phys 2012; 14:13067-75. [DOI: 10.1039/c2cp41825h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bhattacharya S, Panda AN, Meyer HD. Cross sections and rate constants for OH + H2 reaction on three different potential energy surfaces for ro-vibrationally excited reagents. J Chem Phys 2011; 135:194302. [DOI: 10.1063/1.3660222] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Sterpone F, Martinazzo R, Panda AN, Burghardt I. Coherent Excitation Transfer Driven by Torsional Dynamics: a Model Hamiltonian for PPV Type Systems. ACTA ACUST UNITED AC 2011. [DOI: 10.1524/zpch.2011.0117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
A model Hamiltonian is proposed for systems of poly-phenylene-vinylene (PPV) type, which describes excitation energy transfer (EET) in the presence of torsional and bond-length-alternation coordinates that couple neighboring fragments. This model is employed to describe coherent EET, starting from a partially delocalized exciton state which is initially separated from the rest of the chain by a defect due to a pronounced torsional displacement at one of the inter-fragment junctions. EET is found to be driven by the restoring force of the torsions towards the planar geometry. Quantum dynamical calculations are carried out for a minimal five-site model, using the multiconfiguration time-dependent Hartree (MCTDH) method.
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Affiliation(s)
- Fabio Sterpone
- Institut de Biologie Physico-Chimique, Paris, Frankreich
| | - Rocco Martinazzo
- Università degli Studi di Milano, Dipartimento di Chimica-Fisica ed Elettrochimica, Milano, Italien
| | - Aditya N. Panda
- Ecole Normale Supérieure, Départment de Chimie, Paris, Frankreich
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Bhattacharya S, Panda AN, Meyer HD. Multiconfiguration time-dependent Hartree approach to study the OH+H2 reaction. J Chem Phys 2010; 132:214304. [DOI: 10.1063/1.3429609] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Affiliation(s)
- Aditya N. Panda
- Department of Chemistry, Indian Institute of Technology, Guwahati 781039, India
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Abstract
We present the results of a full-dimensional quantum mechanical study of the rovibrational energy transfer in the collision between ortho-H2 and para-H2 in the energy range of 0.1-1.0 eV. The multiconfiguration time-dependent Hartree algorithm has been used to propagate the wave packets on the global potential energy surface by Boothroyd et al. [J. Chem. Phys. 116, 666 (2002)] and on a modification of this surface where the short range anisotropy is reduced. State-to-state attributes such as probabilities or integral cross sections are obtained using the formalism of Tannor and Weeks [J. Chem. Phys. 98, 3884 (1993)] by Fourier transforming the correlation functions. The effect of initial rotation of the diatoms on the inelastic and de-excitation processes is investigated.
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Affiliation(s)
- Aditya N Panda
- Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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