Molecular dynamics study of crystal formation and structural phase transition in Yukawa system for dusty plasma medium

Abstract

The layered crystal formation in dusty plasma medium depicted by the Yukawa interaction amidst dust grains has been investigated using molecular dynamics simulations. The multilayer structures are shown to form in the presence of a combined gravitational and external electric field force (representing the sheath field in experiments) along the ẑ direction. A detailed study of the dependence of the number of crystal layer formation, their width, etc., on various system parameters (viz., the external field profile and the screening length of the Yukawa interaction) has been analyzed. The structural properties of crystalline bilayers have been studied in detail identifying them with the help of pair correlation functions and Voronoi diagrams. It has been shown that the crystalline layers undergo a structural phase transition from hexagonal (often also referred to as triangular) to square lattice configurations when the three-dimensional effects arising from the interaction amidst particles in different layers become important. The simulations show a re-entrant phase transition from the hexagonal to square (and rhombic) structures.