Snapping to commensuration: a numerical investigation of the tendency to epitaxy of lattice mismatched 2D colloidal crystals on periodic optical substrates

Recently T. Bohlein and collaborators carried out an experiment with repulsive colloidal particles trapped in laser interference fields, where they showed that this systems can reveal important aspects on microscopic friction and on the general behavior of discrete elastic layers. In this context, in the present work we investigate, via MD numerical simulations, the tendency of an island of charged colloidal particles to fall into a fully commensurate state, when its natural inter-particle spacing approaches that of a periodically corrugated potential. To this purpose we consider two static metastable states, a commensurate and an incommensurate one, that are local minima of the total energy. Comparing them we produce ground-state phase diagrams highlighting the favorite configuration, whether epitaxial or mismatched and characterized by a network of intersecting (solitonic) dislocation lines. Advisor: Prof. Nicola Manini Co-Advisor: Dr. Andrea Vanossi