Theoretical ground state and excited state potential energy curves for alkali diatomic molecules

Abstract

A previously developed valence electron model is used in theoretical calculations on all of those states of the molecules Li 2, Na 2, K 2, LiNa, LiK and NaK which dissociate either to give two ground state atoms or to give one ground state atom and one atom in the first excited state ( 2 P). Many of the potential curves show stable minima. The results are in good agreement with experimental evidence, for those few states for which the latter is available. In the case of the homonuclear diatomics, difficulties in reproducing the shape of the lowest 1Π u curve are traced to the conclusion that binding in this state results from an avoided crossing with a higher “ionic” 1Π u curve.