Topography of potential-energy surfaces. Spin–orbit interaction for F + F2, Cl + Cl2

Abstract

Potential-energy surfaces have been calculated for the F + F₂ and Cl + Cl₂ reactions using the DIM (diatomics-in-molecules) method including spin–orbit interaction. The non-adiabatic coupling strength between the two lowest Ω= 1/2 potential-energy surfaces shows two maxima for motion along the minimum-energy pathway. One maximum occurs in the entrance valley and the other in the exit valley. These maxima depend both on the translational motion of the longer X—X bond and on the vibrational motion of the shorter X—X bond. The probability of non-adiabatic transition from the lower potential-energy surface, which correlates with ground-state X(²P_3/2) atoms, to the upper potential-energy surface, which correlates with excited state X(²P_1/2) atoms, has its maximum value in the collinear configuration and decreases in bent configurations.