HUA-GEN YU, TREVOR J. SEARS AND JAMES T. MUCKERMAN, Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000 USA.
We present ab initio multi-reference configuration interaction (MRCI) calculations of potential energy surfaces of HCCl in its three low-lying electronic states ( 1A', 3A'' and 1A'') and for the spin-orbit coupling between the and states. The two singlet states become a degenerate 1 state in collinear geometries. The potential energy surfaces are interpolated from 6075 MRCI energy points. The final surfaces are slightly adjusted using a coordinate and energy scaling approach. The Te values of the 3A'' and 1A'' states are computed to be 2122.0 and 12209.8 cm-1, respectively. Vibrational energy levels of the three states of DCCl and HCCl taking into account the Renner-Teller effect and spin-orbit coupling are computed. The calculated vibronic energy levels are in good agreement with the available experimental values.