Physical Review B 78, 174101 (2008)

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

Patricia Silas1, Jonathan R. Yates1 and Peter D. Haynes2

1Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
2Departments of Physics and Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK

We report on our investigation of the crystal structure of arsenic under compression, focusing primarily on the pressure-induced A7 -> 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 -> 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 66×66×66 to enable us to present reliably converged results for the A7 -> sc transition of arsenic.

Last updated: 5 August 2010