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Karton A, Martin JML. Prototypical π-π dimers re-examined by means of high-level CCSDT(Q) composite ab initio methods. J Chem Phys 2021; 154:124117. [PMID: 33810692 DOI: 10.1063/5.0043046] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The benzene-ethene and parallel-displaced (PD) benzene-benzene dimers are the most fundamental systems involving π-π stacking interactions. Several high-level ab initio investigations calculated the binding energies of these dimers using the coupled-cluster with singles, doubles, and quasi-perturbative triple excitations [CCSD(T)] method at the complete basis set [CBS] limit using various approaches such as reduced virtual orbital spaces and/or MP2-based basis set corrections. Here, we obtain CCSDT(Q) binding energies using a Weizmann-3-type approach. In particular, we extrapolate the self-consistent field (SCF), CCSD, and (T) components using large heavy-atom augmented Gaussian basis sets [namely, SCF/jul-cc-pV{5,6}Z, CCSD/jul-cc-pV{Q,5}Z, and (T)/jul-cc-pV{T,Q}Z]. We consider post-CCSD(T) contributions up to CCSDT(Q), inner-shell, scalar-relativistic, and Born-Oppenheimer corrections. Overall, our best relativistic, all-electron CCSDT(Q) binding energies are ∆Ee,all,rel = 1.234 (benzene-ethene) and 2.550 (benzene-benzene PD), ∆H0 = 0.949 (benzene-ethene) and 2.310 (benzene-benzene PD), and ∆H298 = 0.130 (benzene-ethene) and 1.461 (benzene-benzene PD) kcal mol-1. Important conclusions are reached regarding the basis set convergence of the SCF, CCSD, (T), and post-CCSD(T) components. Explicitly correlated calculations are used as a sanity check on the conventional binding energies. Overall, post-CCSD(T) contributions are destabilizing by 0.028 (benzene-ethene) and 0.058 (benzene-benzene) kcal mol-1, and thus, they cannot be neglected if sub-chemical accuracy is sought (i.e., errors below 0.1 kcal mol-1). CCSD(T)/aug-cc-pwCVTZ core-valence corrections increase the binding energies by 0.018 (benzene-ethene) and 0.027 (benzene-benzene PD) kcal mol-1. Scalar-relativistic and diagonal Born-Oppenheimer corrections are negligibly small. We use our best CCSDT(Q) binding energies to evaluate the performance of MP2-based, CCSD-based, and lower-cost composite ab initio procedures for obtaining these challenging π-π stacking binding energies.
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Affiliation(s)
- Amir Karton
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Jan M L Martin
- Department of Organic Chemistry, Weizmann Institute of Science, 76100 Reḥovot, Israel
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Xie H, Zhang H, Cheng X. Collision-Induced Rotational Excitation of CO 2 by N( 4S) Atoms: A New Ab Initio Potential Energy Surface and Scattering Calculations. J Phys Chem A 2021; 125:1134-1141. [PMID: 33507756 DOI: 10.1021/acs.jpca.0c08805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Collisional excitations of CO2 molecules are significant to fully understand the physical and chemical processes of astrophysical and atmospheric environments. Rotational excitations of CO2 molecules induced by N(4S) atoms have been studied for the first time. First, we have computed a new highly accurate ab initio potential energy surface (PES) of a CO2-N(4S) van der Waals complex. The PES has been obtained by employing the partially spin-restricted coupled cluster with open-shell single, double, and perturbative triple excitation method with aug-cc-pVQZ basis sets. The full close-coupling calculations have been performed to compute cross sections for kinetic energies up to 800 cm-1. For all of the excitations, rotational cross sections exhibit an overall decrease with the increase of the energy gaps. Rate coefficients are calculated by averaging the cross sections over a Maxwell-Boltzmann distribution for temperatures ranging from 1 to 150 K. The trends in rate coefficients are in good agreement with those of similar collision systems. The decrease in energy gaps and the increase in temperature are the key factors to enhance the rate coefficients of CO2 excitation. Our study will be useful for accurately establishing the atmospheric model of terrestrial planets and determining the abundance of CO2 and N(4S) in space.
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Affiliation(s)
- Hao Xie
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Hong Zhang
- Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Xinlu Cheng
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China.,Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, China
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Chhabra S, Dhilip Kumar TJ. Quantum Scattering Calculations for Rotational Excitations of C3 by Hydrogen Atom: Potential Energy Surfaces and Rate Coefficients. J Phys Chem A 2019; 123:7296-7302. [PMID: 31353907 DOI: 10.1021/acs.jpca.9b05675] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio calculations are performed to determine new potential energy surfaces for the ground state and low-lying excited states of C3 induced by collision with atomic hydrogen. The calculations are performed using the multireference configuration interaction method including Davidson's correction using aug-cc-pVQZ (augmented correlation consistent polarized valence quadruple zeta) basis sets. Nonadiabatic effects leading to avoided crossings are observed between ground and excited states. The computed points of the ground-state surface are fitted to an analytical form suitable for time-independent quantum scattering calculations of the state-to-state collisional cross sections. The close-coupling calculations are performed up to 1000 cm-1. Resonances are observed at very low energies. Among all the rotational transitions, Δj = 2 is found to be predominant for excitation. After Boltzmann thermal averaging collisional cross sections, rate coefficients for rotational levels j = 0, 2, ..., 8 are obtained and discussed covering the temperature up to 100 K. The magnitude of the state-to-state excitation rate obtained is maximum for j = 0 → 2 transition and decrease for other higher excitations. The results computed in this work will be crucially required to accurately model the abundance of carbon trimer and its hydrocarbon form in space.
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Affiliation(s)
- Sanchit Chhabra
- Department of Chemistry , Indian Institute of Technology Ropar , Rupnagar 140001 , India
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Kodrycka M, Patkowski K. Platinum, gold, and silver standards of intermolecular interaction energy calculations. J Chem Phys 2019; 151:070901. [DOI: 10.1063/1.5116151] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Monika Kodrycka
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA
| | - Konrad Patkowski
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA
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Chhabra S, Kushwaha A, Dhilip Kumar TJ. Quantum dynamics study of rotational transitions of NCCN induced by He collision. J Chem Phys 2018; 149:174312. [PMID: 30408997 DOI: 10.1063/1.5058126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantum dynamics of the molecule cyanogen (NCCN) and its collision with helium taking place in the interstellar medium has been studied. An ab initio potential energy surface of NCCN-He, a van der Waals complex, is generated using the high-level single reference coupled-cluster with single and double and perturbative triple excitation method and aug-cc-pVQZ basis sets. Using the multipole expansion, Legendre coefficients have been calculated and utilized in determining collisional cross sections. Close-coupling calculations have been performed to study rotational excitations for He collision with NCCN. Due to nuclear spin statistics, collision induced transitions have even Δj, while odd Δj transitions are forbidden. The presence of resonances arising from rapid oscillation of cross sections in the low energy region is the result of quasi-bound states in the NCCN-He van der Waals complex. Among all the transitions, Δj = 2 are found to be predominant for excitation. Thereafter, for each transition, the rate coefficients have been calculated which decrease with increasing values of j and Δj. The result of this work will be helpful to accurately model the abundance of cyanogen in stellar atmospheres and interstellar gas.
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Affiliation(s)
- Sanchit Chhabra
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
| | - Apoorv Kushwaha
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
| | - T J Dhilip Kumar
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
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Chhabra S, Dhilip Kumar TJ. Ab Initio Potential Energy Surfaces of C 3 Collision with Proton and Quantum Dynamics of Rotational Transition. J Phys Chem A 2018; 122:5437-5444. [PMID: 29791156 DOI: 10.1021/acs.jpca.8b01588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New ab initio potential energy surfaces have been generated for the ground state and low-lying excited states of the H+ + C3 system using the multireference configuration interaction (MRCI) method with Dunning's augmented correlation consistent polarized valence quadruple-zeta (aug-cc-pVQZ) basis sets. The ground state and low-lying excited states show avoided crossing, indicating nonadiabatic coupling. The anisotropy of the ground-state surface has been analyzed by computing the multipolar expansion coefficients with the frozen C-C equilibrium bond length. The asymptotic potential has been merged with the interaction potential by spline fit. This potential is then used in the full close coupling calculations of rotational excitation in C3 collision with the proton for rotational levels j = 0, 2, 4, 6, 8 at very low collision energy. By averaging the cross sections over a Boltzmann distribution of velocities of the incoming atom, we obtain and discuss corresponding rate coefficients of C3 collision with the proton in the interstellar medium.
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Affiliation(s)
- Sanchit Chhabra
- Department of Chemistry , Indian Institute of Technology Ropar , Rupnagar 140001 , India
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Rocha CMR, Varandas AJC. Accurate ab initio-based double many-body expansion potential energy surface for the adiabatic ground-state of the C3 radical including combined Jahn-Teller plus pseudo-Jahn-Teller interactions. J Chem Phys 2015; 143:074302. [DOI: 10.1063/1.4928434] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- C. M. R. Rocha
- Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - A. J. C. Varandas
- Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
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Dubernet ML, Quintas-Sánchez E, Tuckey P. New potential energy surface for the HCS(+)-He system and inelastic rate coefficients. J Chem Phys 2015; 143:044315. [PMID: 26233137 DOI: 10.1063/1.4926839] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A new high quality potential energy surface is calculated at a coupled-cluster single double triple level with an aug-cc-pV5Z basis set for the HCS(+)-He system. This potential energy surface is used in low energy quantum scattering calculations to provide a set of (de)-excitation cross sections and rate coefficients among the first 20 rotational levels of HCS(+) by He in the range of temperature from 5 K to 100 K. The paper discusses the impact of the new ab initio potential energy surface on the cross sections at low energy and provides a comparison with the HCO(+)-He system. The HCS(+)-He rate coefficients for the strongest transitions differ by factors of up to 2.5 from previous rate coefficients; thus, analysis of astrophysical spectra should be reconsidered with the new rate coefficients.
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Affiliation(s)
- Marie-Lise Dubernet
- LERMA, UMR8112, PSL Research University, Observatoire de Paris, Sorbonne Universités, UPMC Univ Paris 06, CNRS, 5 Place Janssen, 92195 Meudon, France
| | - Ernesto Quintas-Sánchez
- LERMA, UMR8112, PSL Research University, Observatoire de Paris, Sorbonne Universités, UPMC Univ Paris 06, CNRS, 5 Place Janssen, 92195 Meudon, France
| | - Philip Tuckey
- LNE-SYRTE, PSL Research University, Observatoire de Paris, Sorbonne Universités, UPMC Univ Paris 06, CNRS, LNE, 61 Av. de l'Observatoire, 75014 Paris, France
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Smith DGA, Jankowski P, Slawik M, Witek HA, Patkowski K. Basis Set Convergence of the Post-CCSD(T) Contribution to Noncovalent Interaction Energies. J Chem Theory Comput 2014; 10:3140-50. [DOI: 10.1021/ct500347q] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel G. A. Smith
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Piotr Jankowski
- Department
of Quantum Chemistry,
Faculty of Chemistry, Nicolaus Copernicus University, Gagarina
7, 87-100 Toruń, Poland
| | - Michał Slawik
- Department of Applied Chemistry
and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Henryk A. Witek
- Department of Applied Chemistry
and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Konrad Patkowski
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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