Theory of V–V and V–T/R energy transfer for HF (n=1 to 7)+HF (0)

Rate constants for vibrational relaxation of HF in vibrational states n=1 to 7 are calculated semiclassically for HF(n)+HF. The variation with n agrees well with experiment. The absolute values are about 55% of the experimental results. Orbiting collisions are important. The relaxation mechanism found disagrees with three well-known more approximate theories. V–T/R transfer is found to be important especially for the higher levels. A renormalization procedure is suggested as a remedy for the well-known numerical inaccuracy of trajectories with very long-lived collision complexes. This renormalization was not important for the present work.