ELASTIC CROSS-SECTIONS AND ANNIHILATION PARAMETER FOR E(-H-2 SCATTERING USING THE SCHWINGER MULTICHANNEL METHOD())

We report detailed results for positron-H-2 collisions obtained with t he Schwinger multichannel method. Our calculations include annihilatio n parameter, differential, integral, and momentum transfer cross secti ons for energies below the positronium formation threshold. The calcul ations were carried out in the static-plus-polarization approximation with symmetry-resolved cross sections. Energy (temperature) dependence and symmetry-resolved contributions for the annihilation parameter Z( eff) are also reported. Our ab initio integral cross sections are foun d to be in good agreement with the experimental data. [S1050-2947(98)0 4409-6].