Vibrational energy flow region

Throughout the previous studies of IVR/VP processes, the cluster vibrational phase space has been separated into two distinct regions—the high frequency chromophore modes and the low frequency van der Waals modes. When this is the case, virtually the entire contribution to the total density of vibrational states comes from the van der Waals modes. Thus, in the absence of VP, IVR results in the almost complete and irreversible flow of energy from the chromophore to the van der Waals modes. 4-Ethylaniline(4EA)/Ar, N2, CH4 clusters are studied to explore the dynamical consequences of low frequency chromophore modes (Hineman et al. 1993a). 

We turn first to computation of thermal transport coefficients, which provides a description of heat flow in the linear response regime. We compute the coefficient of thermal conductivity, from which we obtain the thermal diffusivity that appears in Fourier s heat law. Starting with the kinetic theory of gases, the main focus of the computation of the thermal conductivity is the frequency-dependent energy diffusion coefficient, or mode diffusivity. In previous woik, we computed this quantity by propagating wave packets filtered to contain only vibrational modes around a particular mode frequency [26]. This approach has the advantage that one can place the wave packets in a particular region of interest, for instance the core of the protein to avoid surface effects. Another approach, which we apply in this chapter, is via the heat current operator [27], and this method is detailed in Section 11.2. 

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