Variational transition state theory: Progress report

Technical Report · Tue Mar 01 00:00:00 EST 1988

OSTI ID:6909338

Truhlar, D G

This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. We have developed and implemented several practical versions of variational transition state theory (VTST), namely, canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (..mu..VT). We have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small/emdash/curvature semiclassical adiabatic (SCSA), large/emdash/curvature version/emdash/3 (LC3), and least/emdash/action (LA) approximations. We have applied the methods to thermal rate constants, using transmission coefficients based on ground/emdash/state tunneling and we have also presented and applied adiabatic and diabatic extensions to calculate rate constants for vibrationally excited reactants. Our general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of our work is the determination or modeling, semiempirically and/or from electronic structure calculations, of potential energy surfaces. In this regard we have developed and implemented new flexible procedures for representing the potential surfaces of reactive systems by global and semiglobal analytic functions. Finally, a new initiative is concerned with including variational and tunneling effects in a thermochemical data base.

• Research Organization: Minnesota Univ., Minneapolis (USA). Dept. of Chemistry
• DOE Contract Number: FG02-86ER13579
• OSTI ID: 6909338
• Report Number(s): DOE/ER/13579-20; ON: DE88013756
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHEMICAL REACTION KINETICS
COMPUTER CALCULATIONS
GASES
P CODES
PROGRESS REPORT
TUNNEL EFFECT
VARIATIONAL METHODS
COMPUTER CODES
DOCUMENT TYPES
FLUIDS
KINETICS
REACTION KINETICS
400201* - Chemical & Physicochemical Properties
400800 - Combustion
Pyrolysis
& High-Temperature Chemistry