Normalized kinetic field potentials for the atom-diatom reactions. Testing the collinear surfaces

The method of constructing the potential energy surface (WW) for the collinear atom-diatom chemical reactions, via the virial theorem from the normalized rotating Morse function (rotated around the united atom) representation (T-RMF) of the electronic kinetic energy, T, is tested by generating various WW surfaces for the H + H—H H—H + H and F + H—H F—H + H collinear reactions, and comparing them with the corresponding ab initio (H3) and LEPS (FHH) surfaces. To obtain the T-RMF parameters, only a knowledge of the coordinates and energy along the zero-virial path (zvp) is required, WW = WW[ZVP]. Two approximations of the ZVP have been used: an analytical fit of the ab initio steepest descent minimum energy path (MEP), and the bond energy/bond order (BEBO) path. Tests of both the WT[MEP] and WW[BEBO] surfaces suggest considerable utility of the T-RMF approach in which the virial theorem and the so called T-normalization condition are employed to a priori control the valleys curvature variations during reaction. A notable feature of the H3WW model surfaces is a relatively good representation of the repulsive wall of the surface.