Variational transition state theory with least-action tunneling calculations for the kinetic isotope effects in the Cl+H/sub 2/ reaction: Tests of extended-LEPS, information-theoretic, and diatomics-in-molecules potential energy surfaces

Journal Article · Wed May 01 04:00:00 EDT 1985 · J. Chem. Phys.; (United States)

OSTI ID:6034401

Tucker, S C; Truhlar, D G; Garrett, B C; Isaacson, A D

We apply conventional and variational transition state theory with least-action-ground-state and other transmission coefficients to calculate the rate constants and kinetic isotope effects for the reaction Cl+H/sub 2/..-->..HCl+H. First we consider collinear reactions and compare the calculated results to accurate quantal results for a given potential energy surface. This tests the dynamical methods and shows that they are reliable enough for testing potential energy surfaces. We then make calculations for the three-dimensional reactions employing 11 potential energy surfaces that have been proposed in previous work. Seven of the surfaces are extended LEPS surfaces, as proposed by Persky, Klein, and Stern; Truhlar, Magnuson, and Garrett; and Valencich and co-workers; one is an information-theoretic-bond-order-plus-anti-Morse-bend surface (called AL/AB) proposed by Agmon, Levine, Truhlar, Magnuson, and Garrett; and the final three surfaces are a diatomics-in-molecules-plus-three-center-terms surface proposed by Baer and Last and two diatomics-in-molecules surfaces proposed by Isaacson and Muckerman. Three of the surfaces (the final surface of Persky, Klein, and Stern; the first surface of Truhlar, Magnuson, and Garrett; and the AL/AB surface: all of which have relatively symmetric saddle points) are shown to be more reasonable than the others for predicting the rate constants and the H/sub 2//D/sub 2/ and the HD/DH kinetic isotope effects. The calculations also indicate that the room temperature rate constants are dominated by quantum mechanical tunneling.

• Research Organization: Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
• OSTI ID: 6034401
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:9; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CHEMICAL REACTION KINETICS
CHLORINE
DEUTERIUM
ELEMENTS
ENERGY
HALOGENS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
POTENTIAL ENERGY
REACTION KINETICS
STABLE ISOTOPES