FAST NUMERICAL-CALCULATIONS OF ION-ATOM COLLISIONS
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abstract
When an ion impinges on an atom, the cross sections for electronic transitions can be described in the independent electron model by functions of single electron amplitudes. A single centered expansion of the time-dependent wave functiion of an electron about the heavier nucleus, with charge ZN, is shown to be moderately successful in explaining the dependence of K-shell hole production on the charge, Zrmp, of the projectile. However, capture of electrons by the projectile is important for a complete understanding and can be incorporated, in principle, in the single-center approach by evaluation of a transition matrix element involving a final state on the projectile. This is not an easy theoretical problem even in an asymmetric (ZpZN) collision, because long times are involved which aggravate the inadequacies of a couple-state calculation where the continuum is replaced by a discrete set of pseudostates. Nevertheless a method has been devised which allows convergence in the truncated expansion of Hilbert states. Comparisons are made to experiment. Future developments are discussed. 1980.