Finite temperature ab initio calculation by path integral Monte Carlo method

We develop the path integral method for quantum chemistry, apply the Monte Carlo method to an evaluation of the path integral, and calculate the ensemble average of the energy. For finite temperature, a simple Monte Carlo evaluation of the path integral brings out the negative-sign problem. In this work, to avoid this problem in the numerical evaluation, we apply the new reweighting method to the Monte Carlo integration, and calculate effectively the ensemble average of the energy for finite temperature. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 471–476, 1997