Variational Approach to Quantum Statistical Mechanics
The path-integral formulation of quantum statistical mechanics has been accomplished several years ago by Feynman , who extended his treatment of quantum mechanics propagator to imaginary times, in order to give the expression for the density operator in the coordinate representation. This approach gives useful tools to reduce quantum statistical mechanics calculations to classical ones, in order to use again the configurational integral and eventually the phase-space integral for the evaluation of the partition function. This turns out to be useful expecially for numerical applications and can be alternative with the Wigner  expansion.
KeywordsPartition Function Effective Potential Continuum Limit Quantum Fluctuation Imaginary Time
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