TIME-DEPENDENT CLOSE-COUPLING CALCULATIONS OF POSITRONIUM FORMATION IN POSITRON-HYDROGEN COLLISIONS

Positronium-formation cross sections from positron-hydrogen collisions are calculated by solving a set of close-coupled, time-dependent part ial differential equations. These cross sections are determined by pro pagating a time-evolving wave packet on a two-dimensional radial latti ce and then projecting the wave function onto the stationary states of the atom. Calculations are performed through L=8 and are extrapolated for L greater than or equal to 9 at energies of 30, 40, and 50 eV, Us ing distorted-wave calculations to determine ionization cross sections at these higher energies. we are able to extract approximate positron ium-formation cross sections from the transfer ionization cross sectio ns. Comparisons are made with experiment. [S1050-2947(98)02702-4].