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New coherent state representation for the imaginary time propagator with applications to forward-backward semiclassical initial value representations of correlation functions

2007; American Institute of Physics; Volume: 126; Issue: 16 Linguagem: Inglês

10.1063/1.2714518

1520-9032

Eli Pollak, Eva Martín-Fierro,

Quantum, superfluid, helium dynamics

There have been quite a few attempts in recent years to provide an initial value coherent state representation for the imaginary time propagator exp(-betaH). The most notable is the recent time evolving Gaussian approximation of Frantsuzov and Mandelshtam [J. Chem. Phys. 121, 9247 (2004)] which may be considered as an expansion of the imaginary time propagator in terms of coherent states whose momentum is zero. In this paper, a similar but different expression is developed in which exp(-betaH) is represented in a series whose terms are weighted phase space averages of coherent states. Such a representation allows for the formulation of a new and simplified forward-backward semiclassical initial value representation expression for thermal correlation functions.