One-Center Molecular Orbitals for HeH++ and HeH+ with Variable Origin

The feasibility of using a variable expansion point in one‐center calculations is investigated for the ground states of HeH⁺⁺ and HeH⁺ with very limited basis sets of Slater‐type atomic orbitals. The energy improvement resulting from variation of the expansion point appears to be economical only if the wavefunction is of the simplest possible form, $\text{1s}$ or $\text{(1s1s)}$ . For these functions the maximum effect of varying the origin occurs in the vicinity of 0.4 a.u., where the improvement in the electronic energy is somewhat less than 2%.