Molecular dynamics simulations study on the melting process of n-heptane layer(s) adsorbed on the graphite (0 0 1) surface

Full atomic molecular dynamics simulations of three kinds of n-heptane layers on the graphite (0 0 1) surface have been performed to investigate their melting process. The melting process and the molecule conformation transition during the process are described at the molecular level. The melting mechanism is suggested by analyzing the conformation transitions during the melting process, which is divided into three stages, i.e. the decrease, the fluctuation and the disappearance of the orientation order. The bond-orientation order parameter along the x-direction, the dihedral distribution and the height distribution of the carbonic atom in the n-heptane layers show different behaviors with increasing temperature. Furthermore, the roles of dihedral and van der Waals energy in the melting process are discussed.