Study of the elastic properties and wave velocities of rocksalt Mg1−xFexO: ab initio calculations

The composition dependence of the elastic constants, bulk modulus, shear modulus, Young's modulus, and compression and shear wave velocities along the different directions for the rocksalt Mg1−xFexO material system has been investigated. The calculations are based on the density functional theory using the full-potential augmented-plane-wave method. The exchange and correlation energies have been treated using three approaches, namely, the local density approximation (LDA), the generalized gradient approximation (GGA) of Perdew et al. and the GGA of Wu and Cohen (WC-GGA). It is found that all the approaches used show the same qualitative behavior for the features of interest versus alloy composition x. From the quantitative point of view, the GGA seemed to give better results than the LDA and WC-GGA approaches when compared to experiment. The trend appears to be consistent with those reported in previous calculations of the elastic constants for other semiconductor materials using the LDA and GGA methods.