Density-functional investigation of the rhombohedral to simple cubic phase transition of arsenic

TL;DR

This study uses density functional theory to analyze the pressure-induced phase transition of arsenic from rhombohedral to simple cubic structure, providing detailed computational insights into transition pressures.

Contribution

It offers a comprehensive computational investigation of arsenic's phase transition using multiple exchange-correlation functionals and dense k-point sampling for accurate transition pressure determination.

Findings

Transition occurs at 21 GPa (LDA), 28 GPa (GGA-PBE), and 29 GPa (GGA-PW91)

No volume discontinuity observed across the transition

High-density k-point grids ensure reliable convergence

Abstract

We report on our investigation of the crystal structure of arsenic under compression, focusing primarily on the pressure-induced A7 to simple cubic (sc) phase transition. The two-atom rhombohedral unit cell is subjected to pressures ranging from 0 GPa to 200 GPa; for each given pressure, cell lengths and angles, as well as atomic positions, are allowed to vary until the fully relaxed structure is obtained. We find that the nearest and next-nearest neighbor distances give the clearest indication of the occurrence of a structural phase transition. Calculations are performed using the local density approximation (LDA) and the PBE and PW91 generalized gradient approximations (GGA-PBE and GGA-PW91) for the exchange-correlation functional. The A7 to sc transition is found to occur at 21+/-1 GPa in the LDA, at 28+/-1 GPa in the GGA-PBE and at 29+/-1 GPa in the GGA-PW91; no volume discontinuity is observed across the transition in any of the three cases. We use k-point grids as dense as 66X66X66 to enable us to present reliably converged results for the A7 to sc transition of arsenic.