Accurate, efficient, and simple forces computed with quantum Monte Carlo methods.
Computation of ionic forces using quantum Monte Carlo methods has long been a challenge. We introduce a simple procedure, based on known properties of physical electronic densities, to make the variance of the Hellmann-Feynman estimator finite. We obtain very accurate geometries for the molecules H(2), LiH, CH(4), NH(3), H(2)O, and HF, with a Slater-Jastrow trial wave function. Harmonic frequencies for diatomics are also in good agreement with experiment. An antithetical sampling method is also discussed for additional reduction of the variance.
Chiesa
Simone
S
Department of Physics, University of Illinois-Urbana-Champaign, Urbana, Illinois 61801, USA. chiesa@uiuc.edu
Ceperley
D M
DM
Zhang
Shiwei
S