Charge exchange, excitation, and ionization via hidden avoided crossings

Abstract

General principles of the asymptotic theory of adiabatically slow atomic collisions are reviewed. Special emphasis is placed on analytic properties of adiabatic potential energy curves for complex values of internuclear separation. The significance of the complex branch points and hidden avoided crossings for the dynamics of one-electron collisional systems is discussed. Adiabatic asymptotes of the cross sections for charge exchange, excitation, and ionization in slow ${\mathrm{He}}^{2+}$+H(1s) and ${\mathrm{H}}^{+}$+${\mathrm{He}}^{+}$(1s) collisions are calculated and compared with other theoretical and experimental data.