Boltzmann wavepacket dynamics on periodic molecular potential functions

The results of a computational study of tunnelling of molecules possessing a single large amplitude vibrational mode with a periodic potential energy function which has equivalent or inequivalent energy minima are described. A time domain description of tunnelling is compared with the frequency domain description given in terms of transitions between stationary states largely localised in distinct potential wells. In particular, the behaviour of Boltzmann wavepackets possessing ensemble average characteristics on such potential functions is described. The role of accidental degeneracies between states with eigenfunctions of appropriate symmetry in mediating tunnelling between inequivalent energy domains on such potential functions is discussed.