H̅ -He elastic scattering at low energies: Contribution of nonzero partial waves

The present study reports the nonzero partial wave elastic cross sections together with s-wave results for the scattering of an antihydrogen atom off a gaseous helium target at thermal energies (up to 10⁻² a.u.). We have used a nonadiabatic atomic orbital method having different basis sets to investigate the system. The consideration of all the significant partial waves (up to J=24) reduces the oscillatory nature present in the individual partial wave cross section. The added elastic cross section is almost constant up to 10⁻⁷ a.u. and then decreases steadily and very slowly with increasing energy.