  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.
