Determination of the accuracy and reliability of molecular dynamics simulations in estimating the melting point of iron: Roles of interaction potentials and initial system configurations

Molecular dynamics (MD) simulations were carried out to investigate the melting transition of iron with an aim to determine the accuracy and reliability of simulated melting points (MP), computing efficiency, and the role played by initial configurations. Two simulation techniques with equilibrium and non-equilibrium heating, and two well-known potentials: Mendelev (EAM) and Etesami (MEAM) were used to investigate a variety of initial configurations containing perfect crystal solid lattice and solid-liquid (S-L) coexistence regions with a number of S-L interfaces and relative S-L proportions (PC, SLSS-2, SLSS-4, SLSS-2 (20%L) and SLSS-2(80%L)). The simulated magnitude of MPs using the non-equilibrium heating method was found to be ~2020 K, which is about 200 K higher than experimental MP of iron (1811 K). Similar values were obtained for both potentials, PC and SLSS-2 configurations; there was a strong evidence for hysteresis effects as well. Simulations with equilibrium heating technique showed that MPs were found to be identical for the wide range of S-L configurations investigated: Mendelev potential (1769 ± 1 K) and Etesami potential (1811 ± 1 K). Corresponding results from the purely solid PC configurations were found to be much higher (1981 ± 1 K and 1951 ± 1 K respectively). Results on other system properties including pair distribution functions, density, local melting and solidification are also reported. These studies have helped identify optimal simulation parameters, potentials and computational approaches to probe the melting region of iron towards applications to problems of industrial importance.