POTENTIAL CURVES FOR THE GROUND AND EXCITED-STATES OF THE NA2 MOLECULE UP TO THE (3S- RESULTS OF 2 DIFFERENT EFFECTIVE POTENTIAL CALCULATIONS(5P) DISSOCIATION LIMIT )

Theoretical calculations for the ground state and for 83 excited state s of the Na2 molecule are presented in the framework of two independen t approaches. The electron-core interaction is represented either by a pseudopotential or by a model potential, and a core polarization pote ntial is introduced in both cases. The basis set contains either Gauss ian orbitals or two-center generalized Slater orbitals. The two method s appear to give similar results, one being more accurate for the grou nd and first excited states, the other being better adapted to the int ermediate Rydberg states. A very good agreement is obtained with the e xperimental spectroscopic constants determined for 26 states, the mean deviation being DELTAR(e)=0.05a0, DELTAomega(e) =0.86 cm-1, and DELTA D(e)=57 cm-1.