title: Path-integral approach to the Wigner-Kirkwood expansion.
abstract: We study the high-temperature behavior of quantum-mechanical path integrals. Starting from the Feynman-Kac formula, we derive a functional representation of the Wigner-Kirkwood perturbation expansion for quantum Boltzmann densities. As shown by its applications to different potentials, the presented expansion turns out to be quite efficient in generating analytic form of the higher-order expansion coefficients. To put some flesh on the bare bones, we apply the expansion to obtain basic thermodynamic functions of the one-dimensional anharmonic oscillator. Further salient issues, such as generalization to the Bloch density matrix and comparison with the more customary world-line formulation, are discussed.
authors.affiliation: FNSPE, Czech Technical University in Prague, Břehová 7, 115 19 Praha 1, Czech Republic and ITP, Freie Universität in Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: Petr
authors.initials: P
authors.lastname: Jizba
authors.affiliation: FNSPE, Czech Technical University in Prague, Břehová 7, 115 19 Praha 1, Czech Republic and Max Planck Institute for the History of Science, Boltzmannstrasse 22, 14195 Berlin, Germany.
authors.forename: Václav
authors.initials: V
authors.lastname: Zatloukal