Knowledge Bank

Ab initio configuration-interaction computations which invoke an effective core potential approximation are used to describe the 26 lowest-lying states of $Li2$. The quality of the computations are assessed by an analysis of the asymptotic long-range behavior of the potentials and by a comparison of the computed vibrational energy levels with those deduced from spectra. Typical asymptotic results are: $C6=1430(1400)e2a05$ for the $11\Sigma +g$ and $13\Sigma +u$ states: $C3=11.14(11.04)e2a02$ for the $21\Sigma +g$ and $23\Sigma +u$ states. (Literature values are in parenthesis). Scaling the calculated $11\Sigma +g$ potential curve against observed vibrational energy spacings gives a dissociation energy $De=8490(8450,8505)cm-1$. We make special mention of ion-pair effects on the structure and spectra of a number of states.