A new potential surface for the reaction O(P-3)+HCl(X(1)Sigma(+))->OH (X(2)Pi)+Cl(P-2)

The ab initio calculations for the lowest (3)A '' surface of the title reaction and fitting of the data to analytic functions are described. This reaction is believed to be important in the chemistry of the stratospheric ozone layer. The majority of ab initio calculations are done at the CASSCF (complete active space self-consistent field) level, using the MOLPRO suite of quantum chemistry programs. The data are fitted to an expansion in terms of Simmons-Parr-Finlan coordinates and Legendre polynomials in the three-body region and smoothly switched over to extended Rydberg expansions for the diatomics in the asymptotic regions. A limited number of calculations at the multireference configuration interaction level have also been done in the saddle point and the asymptotic regions. The implications of these results to the potential surface are also discussed.