Charge exchange in slow collisions of Si3+ with hydrogen atom: Molecular-orbital close-coupling approaches in the adiabatic representation

We have investigated the process of single-electron transfer from the H atoms to the incident Si3+ in the low energy region (0.1 <= E <= 5.0 keV/u) to determine the significance of additional electronic states of (SiH)(3+) and rotational coupling matrix elements. Total and state-selective cross sections are calculated using both quantal and semiclassical molecular-orbital close-coupling (MOCC) approaches based on the molecular state expansion in the adiabatic representation (adiabatic MOCC). A detailed comparison of quantal and semiclassical transition probabilities is reported. The multireference single- and double-excitation configuration interaction (MRD-CI) method is employed to evaluate the adiabatic potentials and nonadiabatic coupling matrix elements of the system. When compared with other theoretical results, our total MOCC cross sections show good agreement with experimental results. At higher energies our results agree nicely with the findings of electron nuclear dynamics (END) calculations.