Melting of Fe-terephthalate layers on Cu(1 0 0) surface with randomly distributed point defects

Abstract

In this theoretical work, we study the influence of the concentration and type of randomly distributed point defects on crystalline solid surfaces on the possibility of self-assembly and thermal stability of surface confined metal-organic networks (SMON). As an example, we chose fundamentally different and well-studied SMONs of Fe-terephthalate on Cu(100) surface: cloverleaf and single-row structures. Using parallel tempering Monte Carlo simulation, we have determined the concentration thresholds for various types of defects above which the SMONs self-assembly is unfavorable. It is shown that the SMONs melting temperatures decrease equally with an increase in the surface concentration of point defects, regardless of the SMON type. Maximum decrease in the SMON melting temperature relative to the homogeneous surface reaches 15–23%, depending on the defect type. Melting of a more “rigid” single-row structure formed only by the coordination bonds is found to occur through the first-order phase transition, while the cloverleaf structure, stabilized mainly by weak hydrogen bonds and long-range substrate mediated interactions, is a continuous phase transition.