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By expanding Feynman path integrals in a Fourier series a practical Monte Carlo method is developed to calculate the thermodynamic properties of interacting systems obeymg quantum Boltzmann statistical mechanics. Working expressions are developed to calculate internalenergies, heatcapacities, and quantum corrections to free energies. The method is applied to the harmonic oscillator, a double-well potential, and clusters of Lennard-Jones atomsparametrized to mimic the behavior of argon. The expansion of the path integrals in a Fourier series is foundto be rapidly convergentand the computational effort for quantum calculations is found to be wlthin an orderof magnitudeof the corresponding classical calculations. Unlike other related methods no specIal techmques are required to handle systems with strong short-range repulsive forces.

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© 1984 American Institute of Physics.This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in D.L. Freeman and J.D. Doll, “A Monte Carlo-Method for Quantum-Boltzmann Statistical Mechanics Using Fourier Representations of Path Integrals,” J. Chem. Phys.,80, 5709-5718 (1984) and may be found at