  The first three dynamic multipole polarizabilities for the ground state of
hydrogen, helium, hydride ion, and positronium hydride PsH have been computed
using the variational Monte Carlo (VMC) method and explicitly correlated wave
functions. Results for the static dipole polarizability by means of the
diffusion Monte Carlo (DMC) method and the finite field approach show the VMC
results to be quite accurate. From these dynamic polarizabilities van der Waals
dispersion coefficients for the interaction of PsH with ordinary electronic
systems can be computed, allowing one to predict the dispersion energy for the
interaction between PsH and less exotic atoms and molecules.

Atomic Physics