A probe of dynamical models using functional sensitivity densities with application to He⁺+Ne(2p⁶)→He+Ne(2p⁵3s) and Li+I→Li⁺+I^-

Abstract

The functional sensitivity densities δ ln σ₁₂(E)/ δlnV _ii (R) for He⁺+Ne(2p ⁶)→He⁺+Ne(2p ⁵3s) reveal that the collisional excitation cross section σ₁₂(E) is insensitive to the additional diabatic curveV 33 included in some models. The negligible sensitivity of σ₁₂(E) toV ₃₃ offers a quantitative validation of the more popular two state model for collisional excitation of Ne by He⁺. The sensitivity profiles for the collisional ionization Li+I→Li⁺+I^- modeled by crossing diabatic curves V ₁₁ (covalent) and V ₂₂ (ionic) shows that the ionization cross section does not depend on inner crossings even when these stem from large distortions in the underlying potential energy curves. The lack of sensitivity to inner crossings establishes the predominant role of the outermost crossing in triggering nonadiabatic transitions.