Reaction cross sections and rate constants for the F+H2 (D2) → HF(DF)+H(D) reactions from quasiclassical trajectory calculations on a potential energy surface

The dependence of the cross sections for the F+H2 and F+D2 reactions on the collision energy has been determined by means of quasiclassical trajectory calculations (QCT) on the Stark and Werner (SW) ab initio potential energy surface (PES). From these data rate constants as a function of temperature have been evaluated. For both reactions, fairly good agreement between the calculated and experimental rate constants is obtained. Our results are compared with previous QCT and quantum mechanical (QM) calculations on other PES, as well as with recent approximate QM results on the SW-PES. The rate constants are in close agreement for the F+D2 reaction, while for F+H2 our values are larger than the ones obtained on the 6SEC-PES. The more orienting character of the SW-PES can explain these differences, when the nuclear spin statistics of H2 and D2 are taken into account.