Mixed Quantum/Classical Theory (MQCT) Approach to the Dynamics of Molecule-Molecule Collisions in Complex Systems

Fuente: arXiv
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Autori principali: Joy, Carolin, Mandal, Bikramaditya, Bostan, Dulat, Dubernet, Marie-Lise, Babikov, Dmitri
Natura: Preprint
Pubblicazione: 2023
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author Joy, Carolin
Mandal, Bikramaditya
Bostan, Dulat
Dubernet, Marie-Lise
Babikov, Dmitri
author_facet Joy, Carolin
Mandal, Bikramaditya
Bostan, Dulat
Dubernet, Marie-Lise
Babikov, Dmitri
contents We developed a general theoretical approach and a user-ready computer code that permit to study the dynamics of collisional energy transfer and ro-vibrational energy exchange in complex molecule-molecule collisions. The method is a mixture of classical and quantum mechanics. The internal ro-vibrational motion of collision partners is treated quantum mechanically using time-dependent Schrodinger equation that captures many quantum phenomena including state quantization and zero-point energy, propensity and selection rules for state-to-state transitions, quantum symmetry and interference phenomena. A significant numerical speed up is obtained by describing the translational motion of collision partners classically, using the Ehrenfest mean-field trajectory approach. Within this framework a family of approximate methods for collision dynamics is developed. Several benchmark studies for diatomic and triatomic molecules, such as H$_2$O and ND$_3$ collided with He, H$_2$ and D$_2$, show that the results of MQCT are in good agreement with full-quantum calculations in a broad range of energies, especially at high collision energies where they become nearly identical to the full quantum results. Numerical efficiency of the method and massive parallelism of the MQCT code permit us to embrace some of the most complicated collisional systems ever studied, such as C$_6$H$_6$ + He, CH$_3$COOH + He and H$_2$O + H$_2$O. Application of MQCT to the collisions of chiral molecules such as CH$_3$CHCH$_2$O + He, and to the molecule-surface collisions is also possible and will be pursued in the future.
format Preprint
id arxiv_https___arxiv_org_abs_2312_02322
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Mixed Quantum/Classical Theory (MQCT) Approach to the Dynamics of Molecule-Molecule Collisions in Complex Systems
Joy, Carolin
Mandal, Bikramaditya
Bostan, Dulat
Dubernet, Marie-Lise
Babikov, Dmitri
Chemical Physics
Quantum Physics
We developed a general theoretical approach and a user-ready computer code that permit to study the dynamics of collisional energy transfer and ro-vibrational energy exchange in complex molecule-molecule collisions. The method is a mixture of classical and quantum mechanics. The internal ro-vibrational motion of collision partners is treated quantum mechanically using time-dependent Schrodinger equation that captures many quantum phenomena including state quantization and zero-point energy, propensity and selection rules for state-to-state transitions, quantum symmetry and interference phenomena. A significant numerical speed up is obtained by describing the translational motion of collision partners classically, using the Ehrenfest mean-field trajectory approach. Within this framework a family of approximate methods for collision dynamics is developed. Several benchmark studies for diatomic and triatomic molecules, such as H$_2$O and ND$_3$ collided with He, H$_2$ and D$_2$, show that the results of MQCT are in good agreement with full-quantum calculations in a broad range of energies, especially at high collision energies where they become nearly identical to the full quantum results. Numerical efficiency of the method and massive parallelism of the MQCT code permit us to embrace some of the most complicated collisional systems ever studied, such as C$_6$H$_6$ + He, CH$_3$COOH + He and H$_2$O + H$_2$O. Application of MQCT to the collisions of chiral molecules such as CH$_3$CHCH$_2$O + He, and to the molecule-surface collisions is also possible and will be pursued in the future.
title Mixed Quantum/Classical Theory (MQCT) Approach to the Dynamics of Molecule-Molecule Collisions in Complex Systems
topic Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2312.02322