Accurate ground-state calculations ofH2+using basis sets of atom-centered Slater-type orbitals

The variational method is used to find the ground-state energy of the molecular hydrogen ion, ${\mathrm{H}}_2^{+}$, by employing a linear combination of atomic orbitals (LCAO) of the Slater type, all with the same exponential parameter ζ. For the equilibrium position, R=2 a.u., eight-digit accuracy was achieved using 21 orbitals on each nucleus, with the highest principal quantum number, N=6. Beyond R=50, thirteen-digit accuracy is obtained. The wave function is given for various LCAO at the equilibrium position. Strategies developed here will be useful in our studies of polyatomic nonlinear molecules.