Convergence of a variational theory of excitation in atomic collisions at intermediate impact velocities

A variational impact parameter approach to the process of direct electronic excitation of atoms by impact of ions at intermediate velocities was shown to be very successful in predicting the saturation of cross sections when the projectile charge is increased. In the present paper, the convergence to steady results promised by the variational procedure is shown to be reasonable. Theoretical predictions stay in good agreement with experimental data in the case of excitation of Fe24+ (1s2) impinging at 400 MeV on various dilute gases (He, N2, Ar, Kr). (orig.)