One- and two-center effects in single ionization in high-energy collisions of protons and hydrogen molecules

Doubly differential and total cross sections for single ionization in ${\mathrm{H}}^{+}\ensuremath{-}{\mathrm{H}}_{2}$ collisions are evaluated in the continuum distorted wave with eikonal initial state model. One- and two-center models are used to represent the target molecule. In the two-center model, the initial orbitals are represented by Hartree-Fock (HF) or density functional methods, while the continuum wave function of the ejected electron is determined on the spherically averaged model potential derived from the ground-state configuration. In the one-center description of the ${\mathrm{H}}_{2}$ molecule, both the initial and final orbitals are represented on the same potential. Cross sections evaluated with the HF description of the target are generally in good agreement with both experimental data and available theoretical calculations. Models describing the motion of the ejected electron in a potential field derived from a two-center description of the molecule underestimate the electron yield at backward emission angles. The inadequacy of these applications is related to the scattering of the electron by the target nucleus, which is more realistically considered in a calculation based on a one-center description of the molecule.