Accession Number : AD0267900

Title :   Asymptotic Expansion of the Bardeen-Cooper-Schrieffer Partition Function by Means of the Functional Method,

Corporate Author : ILLINOIS UNIV URBANA

Personal Author(s) : MUHLSCHLEGEL,B.

Report Date : DEC 1961

Pagination or Media Count : 1

Abstract : The canonical operator associated with BCS model Hamiltonian of superconductivity is represented as a functional integral by the use of Feynman's ordering parameter. General properties of the partition function in this representation are discussed. Taking the inverse volume of the system as an expansion parameter, it is possible to calcula e the thermodynamic potential including terms independent of the volume. This yields a new proof that the BCS variational value is asymptotically exact. Th behavior of the canonical operator for large volume is described and related to the state of free quasiparticles. A study of the terms of the thermodynamic potential which are of smaller order in the volume in the low temperature limit shows that the ground state energy is non-degenerate and belongs to a number eigenstate. (Author)

Descriptors :   *OPERATORS (MATHEMATICS), *QUANTUM STATISTICS, *SUPERCONDUCTIVITY, FUNCTIONS(MATHEMATICS), MEASURE THEORY, SERIES(MATHEMATICS), THERMODYNAMICS

Distribution Statement : APPROVED FOR PUBLIC RELEASE