MCSCF CALCULATION OF THE POTENTIAL CURVES FOR THE LOWEST EIGHT STATES OF $Li_{2}$

Abstract

Our multiconfigurational self consistent field (MCSCF) wave-functions for the lowest 8 states of $Li_{2}$ are built up from a better-than-double zeta STO basis set comprised of 5s, 5p, and 3d functions. Some rather diffuse p and d functions were incorporated to enhance our description of molecular correlation effects. Our potential curves are compared with the results of other calculations and with recent spectroscopic measurements. We argue that our $\Sigma$ state potentials approach spectroscopic quality. For example, for the $X^{1}\Sigma_{g}$ state we find $R_{e} = 2.686$ {\AA} and $D_{e} = 8270 ~cm^{-1}$, which compares nicely with the experimental $result^{1}$ $R_{e} = 2.673$ {\AA} and $D_{e} = 8440 \pm 100 cm^{-1}$.