Accurate electronic energies ofHe2++

Accurate adiabatic potential curves are calculated for the ground state and 11 excited states of ${\mathrm{He}}_2^{++}$ using the James-Coolidge method. The values are the best of all existing results for this system. The number of basis sets used was 75 for ${}_{}{}^1{}_{}{}^{}\Sigma _g^{+}{}_{}{}^{}$ and 57 for ${}_{}{}^1{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$, ${}_{}{}^3{}_{}{}^{}\Sigma _g^{+}{}_{}{}^{}$, and ${}_{}{}^3{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$. The ground-state energy curve has both a dip and a peak. A dip is also expected for the lowest ${}_{}{}^1{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$ state.