Stochastic variational method for elastic scattering

The stochastic variational method is used with a confining potential of the form V=lambda r(12) to generate correlated basis sets capable of accurately describing low-energy elastic scattering. Stabilization concepts are then used to extract the phase shifts and other scattering observables. The method is applied to positron scattering from H and He, and Ps scattering from H and He. The results of the calculations are in uniformly good agreement with previous high quality calculations or with experiment. In particular, the scattering length for Ps-He scattering is found to be 1.566a(0) while the zero-energy (1)Z(eff) was 0.1157. The Ps-He s-wave phase shift is found to be incompatible with experimental momentum transfer cross sections obtained by the Doppler broadening technique.