Self-assembled monolayer formation of linear molecules onto a FCC(111) surface*

The self-organization of molecules deposited over different surfaces have intersting technological applications. The adsorption of linear molecules as well the formation of self-assembled monolayers are considered in response to the experimental evidence for curcuminoids over gold surfaces. These processes are mainly controlled by the surface-molecule and molecule-molecule interactions. By performing computational calculations based on the density functional theory, we have obtained interaction energies for different configurations of two adsorbed molecules over a Au(111) surface. Such molecules were approximated to linear pentamers while the gold surface corresponds to a triangular lattice. This model system was investigated under the framework of Grand Canonical Monte Carlo simulations paying special attention to two quantities: the surface coverage and an order parameter reflecting the molecular alignment over the surface. As expected, the surface coverage is directly proportional to the system pressure (chemical potential). However, for critical values of the chemical potential the molecules present patterns evidencing nematic transitions.