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Kushwaha A, Chahal P, Dhilip Kumar TJ. Rotational dynamics of CNCN by p-H2 and o-H2 collision at interstellar temperatures. J Chem Phys 2024; 161:064302. [PMID: 39120031 DOI: 10.1063/5.0220608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Accepted: 07/23/2024] [Indexed: 08/10/2024] Open
Abstract
The rotational dynamics of isocyanogen (CNCN) is studied for its collision with para (p-) and ortho (o-) hydrogen (H2) in the temperature range of 1-100 K. These temperatures correspond to the cold dense molecular clouds in the interstellar medium where molecular hydrogen is the primary collider. An ab initio 4D potential energy surface (PES) is constructed keeping the two molecules under rigid rotor approximation. The PES is generated using the CCSD(T)-F12b/AVTZ level of theory. The 4D PES is further fitted into a neural network (NN) model, which can augment the surface and account for missing data points within spectroscopic accuracy. This NN-fitted PES is then expanded over a bispherical harmonics function to get radial terms, which are expressed into analytic functions. Thereafter, the cross sections (σ) are computed for rotational transitions of CNCN (j → j') using the close-coupling and centrifugal sudden methods for both p-H2 (jc = 0) and o-H2 (jc = 1) collision till 194 cm-1. In addition, p-H2 (jc = 0, 2) cross sections are also computed using the centrifugal sudden approximation method. The collisional rates are achieved by taking the Boltzmann distribution of σ over the translational energy of H2 till 100 K. Finally, the CNCN-H2 rates are compared to CNCN-He and NCCN-H2 collisional rates. Comparing even and odd transitions for the CNCN-H2 rates show a propensity toward higher rates for even transitions especially for o-H2 collisions considering low-order transitions.
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Affiliation(s)
- Apoorv Kushwaha
- Quantum Dynamics Lab, Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
| | - Pooja Chahal
- Quantum Dynamics Lab, Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
| | - T J Dhilip Kumar
- Quantum Dynamics Lab, Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, India
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Kushwaha A, Dhilip Kumar TJ. 4D potential energy surface of NCCN-H2 collision: Rotational dynamics by p-H2 and o-H2 at interstellar temperatures. J Chem Phys 2023; 159:074304. [PMID: 37602806 DOI: 10.1063/5.0161335] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 07/28/2023] [Indexed: 08/22/2023] Open
Abstract
The rotational excitation rates of NCCN species are studied for its collision with hydrogen (H2) in temperatures ranging from 1 to 100 K. Such collisions can occur in the interstellar medium with H2 in either para (p-) or ortho (o-) state, of which the p-H2 state can be approximated via its collision with He (using a scaling factor) or with a reduced rigid rotor-H2 surface (by averaging over various orientations of H2). In the current work, a four-dimensional (4D) ab initio potential energy surface (PES) is considered to study the collision dynamics of H2 in both p- and o-states and the results are compared with previous approximations. The 4D surface is constructed using the explicitly correlated coupled-cluster method CCSD(T)-F12b with the augmented triple zeta basis AVTZ and then fitted into an artificial neural networks (NN) model to augment the surface and account for missing data points. The radial coefficients are obtained from this NN fitted 4D PES via a least square fit over two spherical harmonics functions. The cross sections (σ) are computed using the close-coupling (CC) method (until 230 cm-1) for both p- and o-H2 collisions, and the rates are obtained by Boltzmann distribution over the translational energy of H2 until 100 K. The o-H2 rates are found to be higher by 25%-30% and 10%-20% compared to the p-H2 rates for Δj = 2 and higher order transitions, respectively. The coupled-state/centrifugal sudden approximated rates are also computed and found to have deviations as large as 40% when compared to CC rates, thus making quantitative descriptions unreliable.
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Affiliation(s)
- Apoorv Kushwaha
- Quantum Dynamics Lab, Department of Chemistry Indian Institute of Technology Ropar, Rupnagar 140001, India
| | - T J Dhilip Kumar
- Quantum Dynamics Lab, Department of Chemistry Indian Institute of Technology Ropar, Rupnagar 140001, India
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Yang D, Guo H, Xie D. Recent advances in quantum theory on ro-vibrationally inelastic scattering. Phys Chem Chem Phys 2023; 25:3577-3594. [PMID: 36602236 DOI: 10.1039/d2cp05069b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Molecular collisions are of fundamental importance in understanding intermolecular interaction and dynamics. Its importance is accentuated in cold and ultra-cold collisions because of the dominant quantum mechanical nature of the scattering. We review recent advances in the time-independent approach to quantum mechanical characterization of non-reactive scattering in tetratomic systems, which is ideally suited for large collisional de Broglie wavelengths characteristic in cold and ultracold conditions. We discuss quantum scattering algorithms between two diatoms and between a triatom and an atom and their implementation, as well as various approximate schemes. They not only enable the characterization of collision dynamics in realistic systems but also serve as benchmarks for developing more approximate methods.
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Affiliation(s)
- Dongzheng Yang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China. .,Hefei National Laboratory, Hefei 230088, China
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Yang B, Zhang P, Qu C, Wang XH, Stancil PC, Bowman JM, Balakrishnan N, McLaughlin BM, Forrey RC. Full-Dimensional Quantum Dynamics of SiO in Collision with H2. J Phys Chem A 2018; 122:1511-1520. [PMID: 29365271 DOI: 10.1021/acs.jpca.7b09762] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Benhui Yang
- Department
of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, Georgia 30602, United States
| | - P. Zhang
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Chen Qu
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - X. H. Wang
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - P. C. Stancil
- Department
of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, Georgia 30602, United States
| | - J. M. Bowman
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - N. Balakrishnan
- Department
of Chemistry, University of Nevada, Las Vegas, Nevada 89154, United States
| | - B. M. McLaughlin
- Centre
for Theoretical Atomic, Molecular and Optical Physics (CTAMOP), School
of Mathematics and Physics, Queen’s University Belfast, The
David Bates Building, 7 College Park, Belfast BT7 1NN, United Kingdom
| | - R. C. Forrey
- Department
of Physics, Penn State University, Berks Campus, Reading, Pennsylvania 19610, United States
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Yang B, Balakrishnan N, Zhang P, Wang X, Bowman JM, Forrey RC, Stancil PC. Full-dimensional quantum dynamics of CO in collision with H2. J Chem Phys 2016; 145:034308. [DOI: 10.1063/1.4958951] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Benhui Yang
- Department of Physics and Astronomy and the Center for Simulational Physics, The University of Georgia, Athens, Georgia 30602, USA
| | - N. Balakrishnan
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
| | - P. Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - X. Wang
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
| | - J. M. Bowman
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
| | - R. C. Forrey
- Department of Physics, Penn State University, Berks Campus, Reading, Pennsylvania 19610, USA
| | - P. C. Stancil
- Department of Physics and Astronomy and the Center for Simulational Physics, The University of Georgia, Athens, Georgia 30602, USA
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Montero S, Pérez-Ríos J. Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments. J Chem Phys 2014; 141:114301. [DOI: 10.1063/1.4895398] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S. Montero
- Laboratory of Molecular Fluid Dynamics @ Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain
| | - J. Pérez-Ríos
- Physics Department, Purdue University, West Lafayette, Indiana 47907, USA
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