Abstract
To make the path-integral Monte Carlo (PIMC) method more effective and practical in application to systems of identical particles with strong interactions, we introduce a combined bead-Fourier (BF) PIMC approach with the ordinary bead method and the Fourier PIMC method of Doll and Freeman [J. Chem. Phys. {bold 80}, 2239 (1984); {bold 80}, 5709 (1984)] being its extreme cases. Optimal choice of the number of beads and of Fourier components enables us to reproduce reliably the ground-state energy and electron density distribution in the H atom as well as the exact data for the harmonic oscillator. Applying the BF method to systems of identical particles we use the procedure of simultaneous accounting for all classes of permutations suggested in the previous work [Phys. Rev. A {bold 48}, 4075 (1993)] with subsequent symmetrization of the exchange factor in the weight function to make the sign problem milder. A procedure of random walk in the spin space enables us to obtain spin-dependent averages. We derived exact partition functions and canonical averages for a model system of N noninteracting identical particles (N=2,3,4,{hor_ellipsis}) with the spin (fermions or bosons) in a d-dimensional harmonic field (d=1,2,3) that provided a reliable test of the developed MCmore » procedures. Simulations for N=2,3 reproduce well the exact dependencies. Further simulations showed how gradual switching on of the electrostatic repulsion between particles in this system results in significant weakening of the exchange effects. {copyright} {ital 1997} {ital The American Physical Society}« less
Published Version
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