ELECTRONIC EXCITATION OF H-2 BY ELECTRON-IMPACT - CLOSE-COUPLING CALCULATIONS USING THE COMPLEX KOHN VARIATIONAL METHOD

The complex Kohn variational method is employed in four-state close-coupling calculations to generate integral and differential cross sections for low-energy electron-impact excitation of the X 1SIGMA(g)+ --> (b 3SIGMA(u)+, a 3SIGMA(g)+, and c 3PI(u)) transitions in H2. The integral cross sections for excitation of the a 3SIGMA(g)+ and c 3PI(u) states from the ground state are found to be significantly different from earlier two-state calculations. The a 3SIGMA(g)+ cross sections are also larger than the most recent experimental results. This discrepancy is traced to the behavior of the differential cross sections at scattering angles near 0-degrees and 180-degrees, where measurements have not been carried out. The differential cross sections we find for H2 are strikingly similar to cross sections for analogous transitions in He. Previous theoretical studies of these transitions in He have also shown the two-state approximation to be inadequate.