A new estimator for nuclear forces in Quantum Monte Carlo
Abstract
The computation of ionic forces in Quantum Monte Carlo methods with a straightforward use of the HellmanFeynman theorem has infinite variance. We introduce two new estimators based on the observation that the swave component of the density, responsible for the divergent variance, gives a null contribution and can be therefore excluded. The resulting estimators are very simple to apply to manybody systems. For variational Monte Carlo, this leads to a straightforward way to calculate all components of ionic forces at once, with very modest additional programming or computational cost. In diffusion Monte Carlo, since the force is calculated using the electronic density, forward walking or reptation QMC is needed for unbiased results. Applications to simple molecular systems are presented.
 Publication:

APS March Meeting Abstracts
 Pub Date:
 March 2004
 Bibcode:
 2004APS..MARA38007C