This article is cited in 5 papers

Perturbation Theory for Density Matrices and the Thermodynamic Potential of a Quantum System

É. A. Arinstein

Tyumen State University

Abstract: We use the generating functional method for the matrix elements of second quantization operators to obtain a high-temperature expansion of the thermodynamic potential of a quantum system. This method permits isolating irreducible parts of matrices, including the particle-density matrices. We derive an equation for the full unary density matrix, which is equivalent to the variational principle for the thermodynamic potential. The thermodynamic functions and the density matrix can thus be found in the framework of the same variational problem.

Received: 03.04.2001
Revised: 08.06.2001

DOI: 10.4213/tmf290

 English version: Theoretical and Mathematical Physics, 2002, 130:1, 45–53

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