Potential energies and cross sections for MgH+

Configuration-interaction (CI) potential curves have been calculated for the ten lowest singlet molecular states of Mg${\mathrm{H}}^{+}$. The $X{}_{}{}^1{}_{}{}^{}\Sigma$, $A{}_{}{}^1{}_{}{}^{}\Sigma$, and $B{}_{}{}^1{}_{}{}^{}\Pi$ molecular states are calculated to be bound by 1.93, 1.93, and 0.18 eV at equilibrium separations 3.16, 3.84, and $4.41a_0$, respectively. These potential-well characteristics are in reasonable accord with analyses performed on spectroscopic data. The CI potential curves were employed in a three-channel scattering calculation to estimate ${\mathrm{H}}^{+}$ + Mg electron-capture cross sections at velocities (0.1-1.4) × ${10}^8$ cm/sec. Capture with excitation of the ion dominates with H + ${\mathrm{Mg}}^{+}$ ($3p$) being the major electron-capture channel at 1 × ${10}^8$ cm/sec. At higher velocities, a classical-trajectory Monte-Carlo method was used to calculate both the electron-capture and impact-ionization across sections for the ${\mathrm{H}}^{+}$ + Mg collision pair. The calculated electron-capture cross sections are in reasonable agreement with the recent measurements of Morgan and Eriksen.