We present a nonperturbative theory to describe multielectronic processes occurring in the course of collisions between an ion and a molecule. The approach is based on the expansion of the electronic scattering wave function onto asymptotic mono- or multicenter states with proper translational conditions and includes both static and dynamical electronic correlations. Therefore, it has a wide application range around intermediate impact velocities $v\approx v_e$, where $v_e$ is the averaged electron velocity in the initial state. As a first application, we report results on single- and double-electron capture processes in He${}^{2+}$-H${}_2$ collisions for impact energies ranging from 0.01 to 25 keV/u. Special emphasis on the prediction of cross sections for double-electron capture into doubly excited states of helium is addressed.

• Received 28 July 2011

DOI:https://doi.org/10.1103/PhysRevA.84.052722