Knowledge Bank

We will present results of an ab-initio MCSCF/CI study of the curve crossing region for linear $KBr2$. The calculations were performed with effective core $potentials1$ for both Br and $K2$ and a valence double zeta plus polarization basis set. A single set of MCSCF orbitals was used to perform the Cl; the configuration list included up to quadruple excitations from a multireference set. The distance between K and the center of mass of $Br2$ was fixed at 15 a. u. which places the system in the region where a vibrational barrier has been postulated. The barrier has been found in a DIM $calculation3$. We have also calculated coupling matrix elements between the diabatic ionic and covalent states. We shall report energies and matrix elements and compare them with estimates obtained from semiempirical $models3,4$.