PATH-INTEGRAL APPROACH TO CORRELATION-ENERGY

The Feynman path integral method is applied to the many-electron probl em of quantum chemistry. We begin with investigating the partition fun ction of the system in question; then, ''a classical path of electron' ' that corresponds to the Hartree-Fock approximation is obtained by mi nimizing the thermodynamic potential of the system with respect to the electron coordinate. The next-order approximation is obtained by eval uating the deviation from this classical path, which is approximately written by an easily integrable Gaussian integral. The result is expec ted to be the random-phase approximation. As numerical examples, the h ydrogen molecule and butadiene are treated. (C) 1994 John Wiley & Sons , Inc.