Comparative study of quantal and semiclassical treatments of charge transfer betweenO+and He

A comparative study for the electron capture process ${\text{O}}^{+}\text{ }({^{4}S}^{0},{^{2}D}^{0},{^{2}P}^{0})+\text{He}\ensuremath{\rightarrow}\text{O}(^{3}P)+{\text{He}}^{+}$ is reported. The cross sections are calculated using fully quantal and semiclassical molecular-orbital close-coupling (MOCC) approaches in the adiabatic representation. Detailed comparison of transition probabilities and cross sections is made from both MOCC approaches and displays close agreement above $\ensuremath{\sim}125\text{ }\text{eV}/\text{u}$. The remarkable discrepancies between the earlier semiclassical and quantal MOCC approaches may be attributed to the insufficient step-size resolution in their semiclassical calculation [M. Kimura et al., Phys. Rev. A 50, 4854 (1994)]. Our results have also been compared with experiment and found to be in good agreement.