Variational Approach to Quantum Statistical Mechanics of Nonlinear Systems with Application to Sine-Gordon Chains

Riccardo Giachetti; Valerio Tognetti

doi:10.1103/PhysRevLett.55.912

Variational Approach to Quantum Statistical Mechanics of Nonlinear Systems with Application to Sine-Gordon Chains

Riccardo Giachetti and Valerio Tognetti

Phys. Rev. Lett. 55, 912 – Published 26 August 1985

Abstract

The path-integral method is used for determination of the quantum corrections to the free energy of nonlinear systems. All quantum effects of the harmonic part of the potential are considered and a variational principle is used to account for the quantum corrections due to the anharmonic part. Correct renormalized frequencies are obtained at any temperature and an effective potential to be inserted in the configurational integral is found. A new general expression for the partition function at any temperature in the low-coupling limit is obtained.

Received 3 January 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.912

Authors & Affiliations

Riccardo Giachetti^* and Valerio Tognetti^†

Dipartimento di Fisica, Università di Firenze, 50125 Firenze, Italy

^*Also at Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Firenze, Italy.
^†Also at Centro Interuniversitario Struttura della Materia, Unità di Firenze, Firenze, Italy.