Phys. Rev. Lett. 94, 036404 (2005) [4 pages]Accurate, Efficient, and Simple Forces Computed with Quantum Monte Carlo MethodsReceived 20 September 2004; published 24 January 2005 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 H2, LiH, CH4, NH3, H2O, 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. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.94.036404
DOI:
10.1103/PhysRevLett.94.036404
PACS:
71.15.–m, 02.70.Rr
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