Evaluation for Validity of Effective Medium Theory in Aluminum Based on Ab Initio Analysis

Abstract

Various types of interatomic potential functions have been proposed for atomic simulations, such as molecular dynamics and Monte Carlo calculation. Those functions are constructed based on the properties at equilibrium states of single crystal. Reliability of the potential functions under the condition far from such states, which is called transferability, is an important factor in the simulations of materials with nanoscopic complex structure or under high stress condition. However, it is not sufficiently investigated because it is difficult to get precise experimental data in such conditions. In this paper, simulations are conducted for aluminum bulk under high strain, grain boundary of aluminum and atomic chain using the potential function of the effective medium theory (EMT) as well as ab initio calculation in order to clarify its validity. In the case of single crystal under tensile strain, the results obtained from the EMT potential agree well with those obtained by ab initio analysis. The EMT gives also good correspondence in the grain boundary structure. However, EMT cannot be applied to the atomic chain because distribution of charge density eminently differs from that in the bulk.