Test of variational transition state theory against accurate quantal results for a reaction with very large reaction-path curvature and a low barrier

Journal Article · Mon Oct 15 04:00:00 EDT 1984 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.448082· OSTI ID:6420670

Truhlar, D G; Garrett, B C; Hipes, P G; Kuppermann, A

We present three sets of calculations for the thermal rate constants of the collinear reaction I+HI..-->..IH+I: accurate quantum mechanics, conventional transition state theory (TST), and variational transition state theory (VTST). This reaction differs from previous test cases in that it has very large reaction-path curvature but hardly any tunneling. TST overestimates the accurate results by factors of 2 x 10/sup 10/, 2 x 10/sup 4/, 57, and 19 at 40, 100, 300, and 1000 K, respectively. At these same four temperatures the ratios of the VTST results to the accurate quantal ones are 0.3, 0.8, 1.1, and 1.4, respectively. We conclude that the variational transition states are meaningful, even though they are computed from a reaction-path Hamiltonian with large curvature, which is the most questionable case.

• Research Organization: Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
• OSTI ID: 6420670
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 81:8; 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
ELEMENTS
HALOGEN COMPOUNDS
HALOGENS
HYDRIODIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
IODINE
IODINE COMPOUNDS
KINETICS
MECHANICS
NONMETALS
QUANTUM MECHANICS
REACTION KINETICS
VARIATIONAL METHODS