Knowledge Bank

The total energy of the $BeH2$ molecule has been estimated as the sum of three terms; the LCAO-SCF energy, the SCF error down to the Hartree-Fock limit, and the correlation energy to the nonrelativistic total energy. The SCF error is taken as similar to that occurring in the ground electronic states of the isoelectronic species C and BH. The correlation energy is estimated from the observation by Clementi that for the hydrides $H2,LiH$, and $CH4$ the formation of covalent bonds from the atoms is accompanied by an increase in correlation energy of about 1.1 ev per bond. The relativistic energy, residing almost exclusively in the Be K shell, is 0.002 atomic units and therefore somewhat beyond the limit of our confidence in the two larger corrections. Numerical results will be presented. Supported by National Aeronautics and Space Administration Research Grant No. NsG-518.