Calculated Potential-Energy Curves for CH+

Abstract

Ab initio calculations have been performed for states of C${\mathrm{H}}^{+}$ which arise from atomic ${\mathrm{C}}^{+}(^{2}P)$ and $\mathrm{H}(^{2}S)\ensuremath{-}X^{1}\ensuremath{\Sigma}^{+}$, $A^{1}\ensuremath{\Pi}$, $^{3}\ensuremath{\Pi}$, and $^{3}\ensuremath{\Sigma}^{+}$. Potential curves have been constructed over a wide range of internuclear distances. All computed energies are believed to be within 1 eV of their exact nonrelativistic Born-Oppenheimer value, and all energy differences are believed to have an accuracy of better than 0.3 eV. Results, with known experimental values in parentheses, are ${R}_{e}(X^{1}\ensuremath{\Sigma}^{+})=2.136$ (2.137) a.u.; ${D}_{e}^{0}(X^{1}\ensuremath{\Sigma}^{+})=4.11$ (4.21) eV; ${R}_{e}(A^{1}\ensuremath{\Pi})=2.232$ (2.333) a.u.; ${T}_{e}(X\ensuremath{-}A)=24970$ (24146) ${\mathrm{cm}}^{\ensuremath{-}1}$; ${R}_{e}(^{3}\ensuremath{\Pi})=2.130$ a.u. No evidence is found for a quasibound $^{3}\ensuremath{\Sigma}^{+}$ Rydberg state, although such behavior has been predicted for isoelectronic BH.