The influence of random pinning on the melting scenario of two-dimensional soft-disk systems

Abstract

We present the results of a computer simulation study of the melting scenario of two-dimensional soft-disk systems with potential $U(r)=\varepsilon(\sigma/r)^n$, $n=12$ and $n=1024$, both in the presence of random pinning and without it. The melting parameters have been determined from analysis of the behavior of equations of state, correlation functions of the orientational and translational order parameters, Young modulus and renormalization group equations. The transition points obtained from these criteria are in good agreement. We have shown that the systems melted in two stages - first-order hexatic phase to liquid transition and the continuous Berezinskii-Kosterlitz-Thouless type crystal-hexatic phase transition. Random pinning widened the hexatic phase, but left the melting scenario unchanged.