New potentials for multiscale simulations of liquid metals

Abstract

Abstract. We present the technique and results for finding norm-conserving pseudopotentials and EAM potentials that can be used to recover atomic and electronic structure of liquid iron at and above the melting point. Pseudopotentials were found by minimizing the energy differences of our results with all-electron reference methods; EAM potentials -by the modified hybridization method proposed earlier by Belashchenko. We show that these potentials are at least as accurate in describing liquid iron as the established potentials in the field.

Iron self diffusion in liquid pure iron and iron-carbon alloys

“…As has been demonstrated on Ti [27] and Ni-Zr [33] experimental self-diffusion coefficients in the liquid state are a vital input for the improvement of interatomic potentials used in molecular dynamics (MD) simulations in the liquid: a calibration of interaction potentials with accurate self-diffusion coefficients resulted in a realistic modeling of various melt properties, including the location of the melting transition and the liquid density. In this context, accurate self-diffusion coefficients in liquid iron and iron-carbon can aid the development of interatomic potentials [18] to explore a range of temperature and pressure, that is otherwise challenging to obtain experimentally: e.g. the study of mass transport coefficients in liquid iron up to Earth-core pressures and temperatures with computer simulation [34,35].…”

“…Reported data indicate a counter example: iron-carbon, where mixing would have a drastic effect on the iron self diffusion-if the values from tracer experiments in Fe-C alloys [16] and liquid iron [19] are accurate. Although liquid Fe-C exhibits a deep eutectic at 17.1 at% carbon [17], the self-diffusion coefficients of Fe in Fe 84 C 16 and Fe 94 C 6 are about 7-9 × 10 −9 m 2 s −1 at 1600 K [16], significantly above the values of pure iron from molecular dynamics computer simulations with various interaction potentials [18] that are in the range of 2.7-3.6 × 10 −9 m 2 s −1 at 1833 K. Experimental self-diffusion coefficients for pure liquid iron have been reported at somewhat elevated pressure: at 2 GPa and at 1883 K the value reads as low as 0.8 × 10 −9 m 2 s −1 [19].…”