skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: MQCT. I. Inelastic Scattering of Two Asymmetric-Top Rotors with Application to H 2O + H 2O

Abstract

A mixed quantum/classical theory (MQCT) for the inelastic collision of two asymmetric-top rotor molecules is developed. Here, the quantum state-to-state transitions between the rotational states of molecules (internal) are treated quantum mechanically using the time-dependent Schrodinger equation, whereas their relative translational motion (responsible for scattering) is treated classically, using the average trajectory approach. Two versions of the formula for transition matrix elements are presented: a straightforward approach that uses numerical multidimensional quadrature over all the internal degrees of freedom and a more standard analytic approach that uses the expansion of the PES over the basis set of spherical harmonics. Adaptation to the case of identical molecules scattering is presented and is applied to the rotational excitation of two water molecules, H 2O + H 2O, using the PES from recent literature. Calculations of collisional excitation from the ground state of the system into a number of low-lying excited rotational states are carried out in a broad range of energies. Analysis of computed opacity functions shows a rather unusual scattering regime, dominated by a strong anisotropic long-range interaction (dipole–dipole). The coupled-states (CS) approximation is tested and found to agree semiquantitatively (within a factor of 2) with the fully coupled version ofmore » the method. Differential cross sections for the elastic scattering suggest a very narrow forward scattering peak.« less

Authors:
ORCiD logo [1];  [1]
  1. Marquette Univ., Milwaukee, WI (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1480253
Grant/Contract Number:  
AC02-5CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 121; Journal Issue: 26; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

Semenov, Alexander, and Babikov, Dmitri. MQCT. I. Inelastic Scattering of Two Asymmetric-Top Rotors with Application to H2O + H2O. United States: N. p., 2017. Web. doi:10.1021/acs.jpca.7b03554.
Semenov, Alexander, & Babikov, Dmitri. MQCT. I. Inelastic Scattering of Two Asymmetric-Top Rotors with Application to H2O + H2O. United States. doi:10.1021/acs.jpca.7b03554.
Semenov, Alexander, and Babikov, Dmitri. Mon . "MQCT. I. Inelastic Scattering of Two Asymmetric-Top Rotors with Application to H2O + H2O". United States. doi:10.1021/acs.jpca.7b03554. https://www.osti.gov/servlets/purl/1480253.
@article{osti_1480253,
title = {MQCT. I. Inelastic Scattering of Two Asymmetric-Top Rotors with Application to H2O + H2O},
author = {Semenov, Alexander and Babikov, Dmitri},
abstractNote = {A mixed quantum/classical theory (MQCT) for the inelastic collision of two asymmetric-top rotor molecules is developed. Here, the quantum state-to-state transitions between the rotational states of molecules (internal) are treated quantum mechanically using the time-dependent Schrodinger equation, whereas their relative translational motion (responsible for scattering) is treated classically, using the average trajectory approach. Two versions of the formula for transition matrix elements are presented: a straightforward approach that uses numerical multidimensional quadrature over all the internal degrees of freedom and a more standard analytic approach that uses the expansion of the PES over the basis set of spherical harmonics. Adaptation to the case of identical molecules scattering is presented and is applied to the rotational excitation of two water molecules, H2O + H2O, using the PES from recent literature. Calculations of collisional excitation from the ground state of the system into a number of low-lying excited rotational states are carried out in a broad range of energies. Analysis of computed opacity functions shows a rather unusual scattering regime, dominated by a strong anisotropic long-range interaction (dipole–dipole). The coupled-states (CS) approximation is tested and found to agree semiquantitatively (within a factor of 2) with the fully coupled version of the method. Differential cross sections for the elastic scattering suggest a very narrow forward scattering peak.},
doi = {10.1021/acs.jpca.7b03554},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 26,
volume = 121,
place = {United States},
year = {2017},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 4 works
Citation information provided by
Web of Science

Save / Share: