Ep. Dasilva et al., ZEFF ACCORDING TO THE SCHWINGER MULTICHANNEL METHOD IN POSITRON SCATTERING, Physical review. A, 49(3), 1994, pp. 180001527-180001530
We use the wave function from the Schwinger multichannel method to cal
culate Z(eff)-an annihilation parameter of positron-atom (or molecule)
scattering. These Z(eff) are evaluated from the (N+1)-particle wave f
unction and are calculated in a fully ab initio way (in a quantum chem
istry sense). Our first applications are for positron scattering again
st He atoms and H-2 molecules. Our results for both systems are in exc
ellent agreement with experimental data at thermal energies.