A LAGROBO Multiproperty Fit to Four-Atom Potential Energy Surfaces: The OH + HCl Case Study†

The four-atom LAGROBO functional form has been used to fit the ab initio potential energy values of the OH + HCl → C+ + H2O reaction. A multiproperty analysis of the fitted surfaces based on the value of the rate coefficients and on the fraction of energy disposed into product vibration has prompted the development of a more general and flexible functional. Using the improved LAGROBO functional, it has been possible to play with the height of the barrier and with the depth of the entrance channel well to significantly reduce the difference between calculated and measured properties of the OH (OD) + HCl reactions.