Résumé
We compare the self-assembly patterns of pentane (C5H12) and hexane (C6H14) adlayers physisorbed onto graphite at various coverages using the results of molecular dynamics simulations. Near monolayer coverage, the solid low temperature structure of the pentane film is nematic, and that of hexane-herringbone-like. At submonolayer coverages both systems exhibit three distinct topological regimes: vacancy patches at higher densities, percolating networks at intermediate densities and ultimately individual patches. The systems' orientational behavior and melting dynamics is discussed with respect to its unique density-dependent topology. The simulations explicitly include hydrogens of pentane and hexane and the graphite is modeled as a six-layer all atom structure. Work supported by the U.S. Department of Energy (DE-FG02-07ER46411) and the American Chemical Society Petroleum Research Fund (PRF43277-B5). Computational resources were provided by the University of Missouri Bioinformatics Consortium.