Theoretical Calculations of Potential Energy Surface and Thermal Rate Constants for the H(Mu) + F₂ Reaction

Abstract

The potential energy surface of the H + F2 → HF + F reaction has been calculated using the ab initio molecular orbital method at the CCSD/6-311++G(3DF,3PD) level of theory. We have found a collinear saddle point with a classical barrier height being 3.7 kcal/mol. Several important characteristics of the potential surface including the location of the saddle point, the bend angle dependence of the potential energy, and the long-range van der Waals interaction have been calculated. These data except for the barrier height were used to develop new potential energy surfaces. Thermal rate constants for the H + F2 and Mu + F2 reactions have been calculated with reduced dimensionality theory using new potential surfaces and compared to experimental results. It has been found that van der Waals interaction plays an important role in low-temperature behavior of rate constants, especially for Mu + F2, where quantum mechanical tunneling should be dominant.