Abstract
We report significant differences in high-pressure properties of vanadium at zero temperature and finite temperature when different projector augmented wave (PAW) potentials are used in simulations based on density functional theory. When a PAW potential with only five electrons taken as valence electrons is used, the cold pressures in the high-pressure region are seriously underestimated, and an abnormality occurs in the melting curve of vanadium at about 400 GPa. We show that the reason for these discrepancies lies in the differences in the descriptions of the interatomic force, electron dispersion, and anisotropy of electron bonding obtained from different PAW potentials at high pressure, which lead to striking differences in the mechanical stability of the system. We propose a procedure for selecting PAW potentials suitable for simulations at high temperature and high pressure. Our results provide valuable guidance for future simulations of thermodynamic properties under extreme conditions.
Highlights
The properties of materials under extreme conditions are of fundamental importance in many areas of science and engineering.1–4 Ab initio methods based on density functional theory (DFT)5,6 have played a key role in the study of matter under high pressure
We report significant differences in high-pressure properties of vanadium at zero temperature and finite temperature when different projector augmented wave (PAW) potentials are used in simulations based on density functional theory
We show that the reason for these discrepancies lies in the differences in the descriptions of the interatomic force, electron dispersion, and anisotropy of electron bonding obtained from different PAW potentials at high pressure, which lead to striking differences in the mechanical stability of the system
Summary
The properties of materials under extreme conditions are of fundamental importance in many areas of science and engineering. Ab initio methods based on density functional theory (DFT) have played a key role in the study of matter under high pressure. PAW datasets for rare-earth elements and transition metals.18 In these studies, the tests on the PAW potentials have been carried out at zero temperature or ambient pressure, thereby providing guidance for calculations under nonextreme conditions. The effects of semicore electrons on the calculation of high-pressure thermodynamic properties of vanadium remain unclear, and there is as yet no definitive standard choice of PAW potential for simulation under high pressure.
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