Vibrational Dynamics ofthe CH4·F–Complex.

Motivated by recent photodetachment experiments studyingresonance structures in the transition-state region of the F + CH4→ HF + CH3reaction, the vibrational dynamicsof the precursor complex CH4·F–isinvestigated. Delocalized vibrational eigenstates of CH4·F–are computed in full dimensionality employingthe multiconfigurational time-dependent Hartree (MCTDH) approach anda recently developed iterative diagonalization approach for generalmultiwell systems. Different types of stereographic coordinates areused, and a corresponding general N-body kineticenergy operator is given. The calculated tunneling splittings of theground and the lower vibrational excited states of the CH4·F–complex do not significantly exceed 1cm–1. Comparing the converged MCTDH results forlocalized vibrational excitations with existing results obtained bynormal-mode-based (truncated) vibrational configuration interactioncalculations, significantly lower frequencies are found for excitationsin the intermolecular modes. [ABSTRACT FROM AUTHOR]