Simulation of structural phase transition in two dimensional ionic crystal

We investigate the structure of a two-dimensional monovalent ionic crystal observed in cationic-anionic molecules adsorbed into surfaces by molecular dynamics simulations. The pair interaction between ions include a short-range Lennard-Jones term and a long-range electrostatic term. When the dielectric constant is small, electrostatic interactions dominate and the crystal form a regular square lattice. At large values of the dielectric constant the Lennard-Jones attraction dominates, and the crystal form a triangular lattice. We study the phase diagram of this model and the properties of the structural transition.