Operator Method for Nonperturbative Calculation of the Thermodynamic Values in Quantum Statistics. Diatomic Molecular Gas

摘要

Operator method and cumulant expansion are used for nonperturbativecalculation of the partition function and the free energy in quantumstatistics. It is shown for Boltzmann diatomic molecular gas with some modelintermolecular potentials that the zeroth order approximation of the proposedmethod interpolates the thermodynamic values with rather good accuracy in theentire range of both the Hamiltonian parameters and temperature. The systematicprocedure for calculation of the corrections to the zeroth order approximationis also considered.