Electron-molecule close coupling with correlated target wave functions: Application to impact dissociation ofF2

An analysis of the close-coupling method as it is traditionally formulated for electron-scattering problems shows that it can give rise to spurious resonances at intermediate energies when multiconfiguration target states are used. These resonances are associated with excited states of the target that are not explicitly included in the close-coupling expansion. We develop a modification of the close-coupling technique that allows one to isolate and systematically eliminate terms from the total wave function which are responsible for the spurious behavior. We have applied this technique to the study of electron-impact dissociation of ${\mathrm{F}}_2$ through its two lowest excited states. The complex Kohn variational calculations we have performed on this system incorporate accurate, multiconfiguration descriptions of the target wave functions.