Unified treatment of slow atom-atom and ion-atom collisions. II. Applications to ${\mathrm{H}}^{+}$+H and ${\mathrm{C}}^{6+}$+H collisions

A unified treatment of ion-atom collisions proposed earlier [Phys. Rev. A 31, 590 (1985)] is applied to study excitation and charge transfer in ${\mathrm{H}}^{+}$+H and ${\mathrm{C}}^{6+}$+H collisions. This method expands the time-dependent electronic wave function in terms of traveling atomic orbitals of the two collision centers at large internuclear separations which is matched to the solution in the inner region where it is expanded in terms of molecular orbitals without translational factors. The results for ${\mathrm{H}}^{+}$+H are shown to agree with recent elaborate close-coupling calculations and with experiments. For ${\mathrm{C}}^{6+}$+H collisions, the partial cross sections for capture to n=5 of ${\mathrm{C}}^{5+}$ are in better agreement with the atomic expansion calculation of Fritsch and Lin than with the molecular orbital expansion of Green et al.