QUANTUM CORRECTIONS TO THE SIMULATED PROPERTIES OF SOLIDS

It is shown that a practical procedure for including both anharmonic a nd quantum effects in the calculation of the properties of solids is t o combine classical molecular-dynamics simulations with quantum correc tions obtained with the quasiharmonic approximation. The procedure is simple to implement and possesses an ordered set of anharmonic quantum corrections. It is tested by calculations on a Lennard-Jones model fo r solid Ar with nearest-neighbor interactions. The results obtained ar e competitive with the predictions of effective-potential Monte Carlo (EPMC) and are in very good agreement with path-integral Monte Carlo r esults, which were obtained with a constant-pressure algorithm that in cludes higher-order corrections to the Trotter expansion. The lowest-o rder perturbative correction to EPMC is shown to be the same as the cu bic part of the anharmonic quantum correction. [S0163-1829(9 8)02302-9 ].