Theoretical confirmation of a high-pressure rhombohedral phase in vanadium metal

Recent diamond-anvil-cell (DAC) experiments revealed a new phase in vanadium metal at high pressure. Here we present results from first-principles electronic-structure calculations confirming the existence of this phase. The structure corresponds to a rhombohedral distortion of the bcc ambient-pressure phase. The calculated transition pressure (0.84 Mbar) and density compare reasonably with the measured data. Interestingly, a reentrant bcc phase is discovered at ultrahigh pressures above 2.8 Mbar, close to the limit of DAC experimental capabilities. We show, extending prior work, that the phase transitions in vanadium are driven by subtle electronic-structure effects.