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Accurate first-derivative nonadiabatic couplings for the H3 system

Abrol, Ravinder and Shaw, Amy and Kuppermann, Aron and Yarkony, David R. (2001) Accurate first-derivative nonadiabatic couplings for the H3 system. Journal of Chemical Physics, 115 (10). pp. 4640-4659. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:ABRjcp01b

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Abstract

A conical intersection exists between the ground (1 2 A[prime]) and the first-excited (2 2A[prime]) electronic potential energy surfaces (PESs) of the H3 system for C3v geometries. This intersection induces a geometric phase effect, an important factor in accurate quantum mechanical reactive scattering calculations, which at low energies can be performed using the ground PES only, together with appropriate nuclear motion boundary conditions. At higher energies, however, such calculations require the inclusion of both the 1 2A[prime] and 2 2A[prime] electronic PESs and the corresponding nuclear derivative couplings. Here we present ab initio first-derivative couplings for these states obtained by analytic gradient techniques and a fit to these results. We also present a fit to the corresponding 1 2A[prime] and 2 2A[prime] adiabatic electronic PESs, obtained from the ab initio electronic energies. The first-derivative couplings are compared with their approximate analytical counterparts obtained by Varandas et al. [J. Chem. Phys. 86, 6258 (1987)] using the double many-body expansion method. As expected, the latter are accurate close to conical intersection configurations but not elsewhere. We also present the contour integrals of the ab initio couplings along closed loops around the above-mentioned conical intersection, which contain information about possible interactions between the 2 2A[prime] and 3 2A[prime] states.


Item Type:Article
ORCID:
AuthorORCID
Abrol, Ravinder0000-0001-7333-6793
Additional Information:© 2001 American Institute of Physics. Received: 11 May 2001; accepted: 19 June 2001 This work has been supported in part by NSF Grant Nos. CHE 9810050 (A.K.) and CHE 9700771 (D.R.Y.).
Funders:
Funding AgencyGrant Number
NSFCHE-9810050
NSFCHE-9700771
Subject Keywords:hydrogen neutral molecules; ground states; excited states; potential energy surfaces; ab initio calculations
Issue or Number:10
Record Number:CaltechAUTHORS:ABRjcp01b
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:ABRjcp01b
Alternative URL:http://dx.doi.org/10.1063/1.1390510
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1142
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:22 Dec 2005
Last Modified:16 Sep 2017 01:29

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