Atomistic simulation of the premelting of iron and aluminum: Implications for high-pressure melting-curve measurements

Using atomistic simulations we show the importance of the surface premelting phenomenon for the melting-curve measurements at high pressures. The model under consideration mimics the experimental conditions deployed for melting studies with diamond-anvil cells. The iron is considered in this work because of the long-standing discrepancies in its melting-curve measurements and its geophysical significance. Results for aluminum are presented for comparison as an opposite case. We calculate the premelting magnitude at different pressures and temperatures and show its influence on the surface roughness that can mislead the experimental determination of the onset of melting in diamond-anvil cells.