Quantum time correlation functions and classical coherence Original Research Article

Quantum time correlation functions for electronically adiabatic and nonadiabatic processes have recently been evaluated directly using the semiclassical initial value representation [J. Cao and G.A. Voth, J. Chem. Phys. 104 (1996) 271]. In this paper, the approach to the classical limit of this theory is analyzed and the nature of coherence in such limits is explored. Article Outline 1. Introduction 2. Semiclassical initial value representation 2.1. Semiclassical Greenʹs functions 2.2. Semiclassical correlation functions 2.3. Sum and difference variables 2.4. Quasiclassical SIVR correlation functions 2.5. Wigner/Weyl and classical limits 3. Illustrative examples 3.1. The harmonic limit 3.2. An anharmonic oscillator 4. Concluding remarks Acknowledgements References