Melting curve and Hugoniot of molybdenum up to 400 GPa by ab initio simulations

TL;DR

This study uses ab initio simulations to accurately determine the melting curve and Hugoniot of molybdenum up to 400 GPa, providing insights into its phase behavior under extreme conditions.

Contribution

It introduces the 'reference coexistence' technique in DFT calculations to improve melting curve predictions of molybdenum at high pressures.

Findings

Melting curve agrees with ambient and shock data but not static experiments.

Hugoniot relations match shock measurements.

Phonon dispersion calculations help interpret phase transitions.

Abstract

We report ab initio calculations of the melting curve and Hugoniot of molybdenum for the pressure range 0-400 GPa, using density functional theory (DFT) in the projector augmented wave (PAW) implementation. We use the ``reference coexistence'' technique to overcome uncertainties inherent in earlier DFT calculations of the melting curve of Mo. Our calculated melting curve agrees well with experiment at ambient pressure and is consistent with shock data at high pressure, but does not agree with the high pressure melting curve from static compression experiments. Our calculated P(V) and T(P) Hugoniot relations agree well with shock measurements. We use calculations of phonon dispersion relations as a function of pressure to eliminate some possible interpretations of the solid-solid phase transition observed in shock experiments on Mo.