Mutual neutralization and chemiionization in collisions of alkali metal and halogen atoms

A semiempirical valence bond method is used to obtain realistic potential curves for the three lowest 1∑+ curves of NaF, KF, LiCl, NaCl, KCl, Lil, and Nal. They are used together with a model functional form for the diabiatic coupling to compute quantal chemiionization and mutual neutralization cross sections. The accuracy of one-electron estimates of the interaction energies in the crossing regions is explored. The Landau–Zener method is found to be very reliable except for collisions involving iodine, for which modifications are necessary.