Quantum Monte Carlo study of pressure-inducedB3−B1phase transition in GaAs

Abstract

We have investigated the transition pressure ${p}_{t}$ of bulk GaAs from the zinc-blende ($B3$) to the rocksalt ($B1$) structure using the local-density approximation (LDA), Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA), and diffusion Monte Carlo (DMC). We took into account finite temperature effects (zero-point vibrational effects) as well as finite-size corrections. Our DMC calculation using GGA trial nodal surface supports the higher value of the transition pressure, $\ensuremath{\sim}$17 GPa, than the lower value of $\ensuremath{\sim}$12 GPa, both of which are experimentally reported values. This projection increases the transition pressure ${p}_{t}$ from DFT predictions, being of the same tendency as that for Si bulk crystal. The choice of the exchange-correlation functional in DFT was found to significantly determine the phase-transition pressure, while DMC gave more accurate results for this transition pressure.