Ground State of the HeH+ Molecule Ion

Abstract

Configuration interaction calculations have been carried out for the system HeH⁺ using one‐electron basis functions in confocal elliptical coordinates. Four internuclear separations, R=1.00, 1.40, 1.80, and 2.20 bohrs (B) were studied rather intensively. One of these, R=1.40 B, lies very close to the equilibrium R and the energies found in this region represent the lowest thus far reported for HeH⁺. Self‐consistent field calculations were also made and in combination with the configuration interaction results lead to an estimation of correlation energies. The binding energy, the equilibrium internuclear separation, and the first few vibrational energies for the system were also estimated. The center of negative charge, which is closely related to the dipole moment, was studied as a function of R and of the size of the one‐electron basis.