Theoretical methods for the study of chemical dynamics
- California Univ., Berkeley, CA (USA). Dept. of Chemistry
Theoretical methods are developed for studying the dynamics of chemical reactions. Many chemical processes can be adequately described as a system'' of one or two reaction coordinates coupled to a bath'' of harmonic oscillators. Such a formulation of the problem has obvious advantages as it is often possible to integrate out the harmonic bath, thus reducing the many degree of freedom problem to a one or two dimensional calculation. A simple semiclassical model for incorporating tunneling effects in classical trajectory simulations is constructed and shown to give excellent results over a variety of conditions. Feynman path integration provides an exact way of calculating quantum, dynamical properties and is in principle applicable to problems of involving many degrees of freedom. However, the standard Monte Carlo methodology which must be used to evaluate the multidimensional integrals that occur, is not directly applicable to the path integral expression for the real time propagator, because the integrand of the latter is highly, oscillatory. A technique which helps circumvent this problem by sampling about the stationary phase points of the integrand is developed and illustrated with several numerical applications. A new effective real time propagator is also constructed, which is localized and devoid of rapid oscillations. Finally, accurate approximations to the short time propagator are derived, which drastically improve the convergence characteristics of path integrals. These techniques are expected to extend the applicability of path integral calculations to more complex chemical problems. 258 refs., 63 figs., 3 tabs.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5417711
- Report Number(s):
- LBL-27938; ON: DE90003122
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL REACTIONS
DYNAMICS
CHEMICAL REACTION KINETICS
FEYNMAN PATH INTEGRAL
MONTE CARLO METHOD
PROPAGATOR
QUANTUM MECHANICS
INTEGRALS
KINETICS
MECHANICS
REACTION KINETICS
400201* - Chemical & Physicochemical Properties
657002 - Theoretical & Mathematical Physics- Classical & Quantum Mechanics