Abbreviated Journal Title
Phys. Rev. A
Optics; Physics; Atomic; Molecular & Chemical
Electron translation factors (ETF's) appropriate for slow atomic collisions may be constructed using switching functions. In this paper we derive a set of switching functions for the H2+ system by an analytical "two-center decomposition" of the exact molecular eigenstates. These switching functions are closely approximated by the simple form f=bη, where η is the "angle variable" of prolate spheroidal coordinates. For given united atom angular momentum quantum numbers (l,m), the characteristic parameter blm depends only on the quantity c2=-∊R22, where ∊ is the electronic binding energy and R the internuclear distance in a.u. The resulting parameters are in excellent agreement with those found in our earlier work by a heuristic "optimization" scheme based on a study of coupling matrix-element behavior for a number of H2+ states. An approximate extension to asymmetric cases (HeH2+) has also been made. Nonadiabatic couplings based on these switching functions have been used in recent close-coupling calculations for H+-H(1s) collisions and He2+-H(1s) collisions at energies 1.0-20 keV.
Physical Review A
Thorson, W. R.; Kimura, M.; Choi, J. H.; and Knudson, S. K., "Analytically Derived Switching-Functions For Exact H-2(+) Eigenstates" (1981). Faculty Bibliography 1980s. 116.