EAM-Cu 2D Melting's Computer Simulation

The nature of phase transitions in two-dimensional systems remains one of the forefront problems in statistic physics. This kind of transition has many different characters and influences other disciplines profoundly, and numerous investigations of the 2D melting phase transition have been reported. Here, the computer simulation model is Cu system;particles interaction potential is EAM potential. Our study explores the melting forms, mechanisms and dynamical heterogeneities.In the situation of NPT T=1590K, we analysis correlation functions g(r) and function g₆(r) and combine diffraction patterns to prove the appearance of the intermediate "hexatic phase" during the melting process. By comparing correlation lengths of g(r) and g₆(r), and order parameter GOOP, GTOP, we can define the time zone of the existence of hexatic phase. These illustrate the melting process of EAM-Cu experience solid , hexatic and liquid phase. The results are in agreement with the prediction of the KTHNY theory. By changing the simulation conditions to NVT T=1600K we find the hexactic phase can exist for a rather long time.We use classical nuleation theory to study the melting mechanisms. By means of identifying "liquid atoms" from "solid atoms", and tracing evolution of liquid clusters eliminate the probability of first order transition. We also explore the defects patterns, inherent structure etc, and find that dislocations and disclinations' behavior are different from prediction of KTHNY theory. Uniquely the hole and the interactions between the hole may play an important role during the phase transition.We computer the displacement correlation function d(r),time correlationfunctions α₂(t), G_s(t), ,and time-dependent, four-point density correlation function x₄ (t) to further study the atomic dynamical behaviors during 2D melting process. We find the dynamics from solid to hexatic phase is heterogeneous in character. Further study indicates the heterogeneity may relate with the relative slipping of the atoms.