Single and double charge transfer inBe4++He collisions: A molecular (Feshbach) approach

In recent articles, we pointed out the fundamental difference between the molecular treatment of processes involving a multicharged ion and hydrogen or helium atoms, which is the (formal) autoionizing character of the molecular channels, and we reported a (new) implementation of the Feshbach method to calculate the molecular energies and couplings. In the present work we use the wave functions calculated with this Feshbach method for the ${\mathrm{BeHe}}^{4+}$ quasimolecule, introduce a common translation factor in the formalism, and calculate the single and double charge-exchange cross sections in ${\mathrm{Be}}^{4+}$+He(1$s^2$) collisions for impact energies 0.2–20 keV/amu. The mechanisms of the processes are discussed in detail.