'Graphenization' of 2D simple monatomic liquids

We present molecular dynamics (MD) simulations of the formation of 2D materials with a honeycomb structure from 2D simple monatomic liquids with honeycomb interaction potential (Rechtsman et al 2005 Phys. Rev. Lett. 95 228301). Models are observed by cooling from the melt at various cooling rates. Thermodynamics of the phase transitions is analyzed in detail. Depending on the cooling rate, amorphous or crystalline honeycomb structures have been found. Structural properties of the crystalline honeycomb structure are studied via radial distribution function (RDF), coordination number and ring distribution, including 2D visualization of the atomic configurations. We find evidence for the existence of polycrystalline honeycomb structures and new structural defects, not previously reported. The atomic mechanism that forms the solid phase of a honeycomb structure from the liquid state has been analyzed by monitoring the spatio-temporal arrangement of atoms in 6-fold rings and/ or atoms with the coordination number Z = 3, occurring upon cooling from the melt. Since knowledge of how real 2D solids with honeycomb structures form from the vapor or liquid phase is still completely lacking, our simulations highlight the situation and give a deeper understanding of the structure and thermodynamics of real 2D materials such as graphene, silicene, germanene, etc.