Abstract
The flux-flux correlation function formalism is a standard and widely used approach for the computation of reaction rates. In this paper we introduce a method to compute the classical and quantum flux-flux correlation functions for anharmonic barriers essentially analytically through the use of the classical and quantum normal forms. In the quantum case we show that for a general f degree-of-freedom system having an index one saddle the quantum normal form reduces the computation of the flux-flux correlation function to that of an effective one-dimensional anharmonic barrier. The example of the computation of the quantum flux-flux correlation function for a fourth order anharmonic barrier is worked out in detail, and we present an analytical expression for the quantum mechanical microcanonical flux-flux correlation function. We then give a discussion of the short-time and harmonic limits. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518425]
Original language | English |
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Article number | 244113 |
Number of pages | 8 |
Journal | Journal of Chemical Physics |
Volume | 133 |
Issue number | 24 |
DOIs | |
Publication status | Published - 28-Dec-2010 |
Keywords
- TRANSITION-STATE THEORY
- REACTION-RATE CONSTANTS
- PHASE-SPACE
- CHEMICAL-REACTIONS
- NONSEPARABLE SYSTEMS
- SEMICLASSICAL THEORY
- QUANTUM-MECHANICS
- DAMPED SYSTEMS
- PROBABILITIES
- CONSTRUCTION