MOLECULAR-DYNAMICS SIMULATIONS OF A FLEXIBLE MOLECULE IN A LIQUID-CRYSTALLINE SOLVENT

Molecular dynamics simulations of a hexane molecule in isotropic, nema tic, and smectic phases are reported. The interactions between the sol vent molecules is modeled using the Gay-Berne potential and the hexane -solvent potential is modeled as an explicit site-site interaction. Th e conformational distributions are reported of the hexane molecule at a fixed temperature but at different densities in isotropic, nematic, and smectic phases, and these are compared with the results from Monte Carlo simulations on an isolated molecule at the same temperature. Th e positions and orientations of the hexane molecule at each time step in the molecular dynamics simulations are used to calculate interproto n dipolar coupling constants. These data are used to test the mean fie ld models which have been applied with dipolar couplings obtained prev iously from nuclear magnetic resonance (NMR) experiments to yield conf ormational distributions.