Classical Intramolecular Energy-Transfer Rates Using Fourier Transform Methods:Four-Atom Systems

摘要

A previously reported Fourier transform method for computation of classicalintramolecular mode-to-mode energy-transfer rate coefficients is extended to four-atom molecules. HONO and C2H2 are used as test cases. The method involves the Fourier transform of the time variation of a local-mode bond energy for an ensemble of trajectories. A two-mode, collinear model is employed to demonstrate that the transform is expected to contain a series of spectral bands at frequencies corresponding to the mode-to-mode energy-transfer rates. Heavy-atom blocking and constrained motion methods are employed to determine the individual band assignments. The results for both HONO and C2H2 are in good accord with the total relaxation rate extracted from decay plots of the local-mode energy. Intramolecular energy transfer.