Embedded-atom molecular dynamic study of iron melting

The embedded-atom method (EAM) was applied to calculate thermoelastic properties of iron phases with emphasis on very high pressures and temperatures. Calculated properties of different solid phases are in good agreement with experiment and also phase relations are reasonably well reproduced. EAM equations of state of alpha-, epsilon-, and gamma-iron at zero temperature are consistent with ab initio full-potential linear muffin-tin-orbital results up to very high compression. The molecular dynamic simulations show that above 50 GPa epsilon-iron is the most stable solid phase. The zero pressure melting point of gamma-iron is close to 1500 K which is somewhat lower than the experimental value. The structure of the liquid phase and the volume change at melting are in very good agreement with experiment. The melting curve simulated by the two-phase method is in better agreement with the high melting temperatures obtained from shock-wave experiments than with the data recently obtained using diamond-anvil cell technique combined with laser heating. Analysis of possible errors show that the likely melting temperature of iron at the pressure of the inner/outer Earth's core boundary is about 7500 K, according to this study. (C) 1997 Elsevier Science B.V.