Molecular Dynamics Simulation of Energy Transport in Molecular Solids

This dissertation is concerned with molecular dynamics simulation of energy transport in molecular crystals. Semiclassical dynamical methods for shock wave propagation and energy redistribution among intramolecular and intermolecular vibrational modes in molecular crystals have been developed and applied to various 1-D and 2-D Morse molecular lattices. In the semi-classical methods, a group of molecules are chosen as a cluster and the exact quantum eigenstates for a cluster are first found and the interactions between neighboring clusters are then considered as time-dependent perturbations which induce transitions among the cluster eigenstates. Classical trajectory calculations have also been performed for these molecular lattices. Then classical and semiclassical results were compared. Calculational results using the semiclassical cluster model qualitatively agreed with classical calculational results, but quantitative differences did arise because of anharmonic potentials. Therefore, quantum effects did exist for anharmonic lattices. It was also found that energy was not uniformly distributed among various vibrational modes.