Pseudopotential spin-density functional calculation of the ground state properties of Na₂ and Na₂⁺

The potential energy curves for the ground states of Na₂ and Na₂⁺ are calculated within the local spin-density approximation, using model pseudopotentials to simulate core effects. Our results compare very well with the experimental data and the results of much more elaborate configuration interaction calculations. We also find that at intermediate nuclear separations, where the local density approximation breaks down, the local spin-density formalism still allows a good description of the binding energy curve.