Dissociation Energies ofHe2+(X2Σu+)andHe2(A1Σu+)

Abstract

The configuration-interaction method is applied to calculate the dissociation energy of ${{\mathrm{He}}_{2}}^{+}({X}^{2}{{\ensuremath{\Sigma}}_{\mathrm{u}}}^{+})$, yielding a rigorous lower bound of 2.454 eV and a best value of 2.469 \ifmmode\pm\else\textpm\fi{}0.006 eV. These results are used, in combination with available spectroscopic data on vibrational states of the ${A}^{1}{{\ensuremath{\Sigma}}_{u}}^{+}$ state of ${\mathrm{He}}_{2}$, to unequivocally make an assignment of 2.549\ifmmode\pm\else\textpm\fi{}0.012 eV for the apparent dissociation energy and to predict a barrier height of 0.080\ifmmode\pm\else\textpm\fi{}0.018 eV for this state.