Homopolymer adsorption on periodically structured surfaces in systems with incommensurable lengths

Surface-induced selective adsorption of homopolymers on a generic level is numerically analyzed for freely jointed chains (with a fixed bond length) whose monomers are attracted by the sites of regular periodic patterns. In particular, the behavior of the specific heat, the gyration tensor, and the bond order tensor are investigated as functions of the temperature. The properties of the transition are related to the interplay of the characteristic lengths. The adsorption proceeds in two steps for certain incommensurabilities of the bond length and the lattice constant. The corresponding adsorption mechanisms are elucidated by looking at the evolution of the inter bond angle distribution upon adsorption. Moreover, the origin of two steps in contrast to adsorption in one step is traced back to entropic restrictions caused by a strongly reduced phase space of the polymer for certain values of the incommensurability.