First-principles study of structural stability and elastic properties of the ordered Si_(0.5)Ge_(0.5) alloy under high pressure

摘要

An investigation on electronic and elastic properties of the ordered Si_(0.5)Ge_(0.5) alloy under high pressure has been conducted using first-principles calculations based on density functional theory (DFT) with the plane wave basis set as implemented in the CASTEP code. Our results demonstrate that the sequence of the pressure-induced structure transition of the ordered Si0.5Ge0.5 alloy is from the Fd3m (Si_(0.5)Ge_(0.5)-I) to I41/amd (Si_(0.5)Ge_(0.5)-II) phase. The calculated lattice constants and transition pressures are reported, which are in good agreement with the available experimental results and the previous theoretical data. The elastic constants and anisotropy as a function of pressure are presented.