Diffusion quantum Monte Carlo study of martensitic phase transition energetics: The case of phosphorene

Recent technical advances in dealing with finite-size errors make quantum Monte Carlo methods quite appealing for treating extended systems in electronic structure calculations, especially when commonly used density functional theory (DFT) methods might not be satisfactory. We present a theoretical study of martensitic phase transition energetics of a two-dimensional phosphorene by employing diffusion Monte Carlo (DMC) approach. The DMC calculation supports DFT prediction of having a rather diffusive barrier that is characterized by having two transition states, in addition to confirming that the so-called black and blue phases of phosphorene are essentially degenerate. At the same time, the DFT calculations do not provide the quantitative accuracy in describing the energy changes for the martensitic phase transition even when hybrid exchange-correlation functional is employed. We also discuss how mechanical strain influences the stabilities of the two phases of phosphorene. Published by AIP Publishing.