Showing papers by "Igor Bray published in 1989"

Coupled channels in the distorted-wave representation.

Abstract: The scattering of electrons or positrons to discrete states of an atomic target is represented in momentum space by coupled integral equations. By introducing a local central potential one may set up a distorted-wave representation for the integral equations, which can be solved to arbitrary numerical accuracy by quadratures. The perturbative solutions of these equations are the commonly used distorted-wave first- and second-order Born approximations. The full coupled on-shell solution is the distorted-wave unitarized Born approximation. These approximations are tested for charged and uncharged targets. The formalism for inclusion of configuration interaction in the target is described, making a complete theory for electron-atom scattering in a truncated channel space, which can be extended by optical potentials to a fully realistic situation.

Full optical potential for the electron-hydrogen entrance channel

Abstract: Differential and total elastic and total reaction cross sections are calculated for electron-hydrogen scattering at 30, 100, and 400 eV using an {ital ab} {ital initio} optical potential that treats bound and continuum nonelastic channels in the distorted-wave Born approximation. Multichannel and partial wave expansions are carried out to numerical convergence. Convergence criteria and quadratures for the continuum-energy integration are chosen for 1% overall accuracy. Results are compared with experiment and less detailed calculations.