  A simple scheme is described for introducing the correct cusps at nuclei into
orbitals obtained from Gaussian basis set electronic structure calculations.
The scheme is tested with all-electron variational quantum Monte Carlo (VMC)
and diffusion quantum Monte Carlo (DMC) methods for the Ne atom, the H2
molecule, and 55 molecules from a standard benchmark set. It greatly reduces
the variance of the local energy in all cases and slightly improves the
variational energy. This scheme yields a general improvement in the efficiency
of all-electron VMC and DMC calculations using Gaussian basis sets.
