Abstract:
We have investigated the transition pressure pt 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, ∼17 GPa, than the lower value of ∼12 GPa, both
of which are experimentally reported values. This projection increases the transition pressure pt 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.
