THE POTENTIAL-ENERGY SURFACE OF THE CAHF SYSTEM

A potential energy function for the CaHF system has been obtained which fits published ab initio Two-Configuration Direct Minimization data at a quantitative level, i.e. with a root-mean-square error of about 1-2 kcal mol(-1), and preserving the accuracy of the ab initio points. The features of this potential have been compared with a previously reported potential function for this system. Several very accurate calculations of selected points of this potential have been made. The true transition state for the Ca + HF --> CaF + H reaction is 14.6 kcal mol(-1) above the reactants at about R(CaF) = 4.18 a.u., R(HF) = 2.54 a.u. and Ca-F-H = 78 degrees. A modified version of the CaHF potential energy surface has been obtained that fits all the features predicted by the most accurate calculations.