STRUCTURE, MELTING AND DYNAMICS OF SCREENED COULOMB-SYSTEMS IN 2D - ROLE OF SUBSTRATE CORRUGATION

MAHANTI-SD, SEONG-H, SEN-S and CAGIN-T

MOLECULAR CRYSTALS AND LIQUID CRYSTALS A 244 141-146(1994)

ABSTRACT

Physical properties of a large class of intercalation compounds can be modeled by a two-dimensional (2D) repulsive screened Coulomb system subjected to a substrate corrugation potential. Using molecular dynamics simulation, we have investigated structural, thermodynamic (mainly 2D melting), and dynamic properties of these systems for different intercalant concentrations and corrugated strengths. For parameters appropriate to RbC24, a stage-2 graphite intercalation compound (GIC), we obtain an incommensurate ground state structure consisting of nano domains of root 7 x root 7 triangular plaquettes separated by thick domain walls. A small decrease in the density gives a commensurate periodic domain wall ground state. In contrast to the corrugation-free systems, melting in these systems is continuous. Dynamics in the presence of corrugation show characteristics of a marginal fluid where solid and fluid-like dynamics coexist.