Influence of electronic correlation on the electron impact excitation of the doubly excited³Pgand¹,³Dustates of helium. II. Rudge-type approximations

For pt.I see ibid., vol.11, no.13, p.2377 (1978). Regional wavefunctions of the type proposed by Rudge have been used to construct estimates of the integral and differential cross sections for the parity-unfavoured 1 S g to 3 P g and 1 S g to 1,3 D u transitions of helium. Both single- and multi-configurational ground-state wavefunctions are tested. Results obtained by using the Born-Oppenheimer approximation are found to be quite insensitive to the choice of ground-state wavefunction. Cross sections computed in this way are similar to previous Born-Oppenheimer results based on conventional continuous wavefunctions for the target states. However, calculations based on the Rudge variation principle are found to depend very sensitively on the choice of target wavefunction and to exhibit several other unexpected characteristics.