REDUCTION OF THE COMPUTATIONAL EFFORT IN QUANTUM MONTE-CARLO CALCULATIONS WITH PSEUDOPOTENTIALS THROUGH A CHANGE OF THE PROJECTION OPERATORS

The usual form of nonlocal pseudopotentials which project the wave function on real spherical harmonics is inconvenient in quantum Monte Carlo calculations because the projection integrals are still functions of r. It is thus necessary to calculate the integral in every point of the simulation. We circumvent this problem by transforming the pseudopotential to a form where the projection occurs on Cartesian Gaussian-type functions which makes the projection integrals independent of the electron coordinates. We applied our method to two-valence electron systems using the pure diffusion method, where the approximation in the pseudopotential is the only one present.