Molecular dynamics studies of the structure and dynamics of ``perpendicular'' layers of \textit{n}-alkane molecules adsorbed on a solid substrate

Both AFM and ellipsometry studies of $n$-alkane films adsorbed on a solid substrate from a solution have shown interesting wetting and de-layering phenomena$^{2}$. It was found that on top of one or two ``parallel'' layers of molecules, where the long axis of the molecules is parallel to the surface, ``perpendicular'' layers of molecules are formed with the long axis of the molecules perpendicular to the surface. MD simulations of layers of tetracosane, $n$-C$_{24}$H$_{50,}$ molecules are set up to answer the following questions about the ``perpendicular'' layers: a) Is the melting transition driven by \textit{gauche} defect creations in the alkane chains like in the parallel layers?, b) can a rotator phase be identified?, c) is there a lateral translational mobility of the chains prior to melting?, and d) what is the mechanism driving the wetting and de-layering transitions in the films? $^{2}$H. Mo et al. Chem. Phys. Lett. \textbf{377}, 99 (2003)