DIFFERENTIAL SCATTERING AND ROTATIONAL-EXCITATION IN LOW-ENERGY POSITRON-HYDROGEN-MOLECULE COLLISIONS

Differential cross sections are calculated for positron-hydrogen-molec ule scattering below the positronium formation threshold using K-matri x elements obtained by the Kohn variational method. The internuclear s eparation of the hydrogen molecule is fixed at its equilibrium value, 1.4a(0). The trial function used in the Kohn calculation is very flexi ble. It contains separable and Hylleraas-type basis functions and also basis functions to take into account long-range polarization. The cro ss sections for rotational excitation are also calculated, using the a diabatic-rotation approximation. Preliminary results are presented in this paper; full details will be published elsewhere.