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We present a new collocation-based multi-configuration time-dependent Hartree (MCTDH) approach for solving the Schrödinger equation required to compute (ro-)vibrational spectra, photodissociation cross sections, reaction rate constants, etc., that can be used with general potential energy surfaces. Collocation obviates the need for quadrature and facilitates using complicated kinetic energy operators. When the basis is good, the accuracy of collocation solutions to the Schrödinger equation is not sensitive to the choice of the collocation points. We test the collocation MCTDH equations we derive by showing that they can be used to compute accurate vibrational energy levels of CH3. It is possible to choose (imaginary) time-independent collocation points with which collocation-based MCTDH energies are accurate. It is therefore not necessary to calculate potential values many times during the propagation. [ABSTRACT FROM AUTHOR]

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]