Electronic and optical properties of LiMgN, LiMgP and LiMgAs under hydrostatic pressure

First principles calculations, by means of the full-potential linearized augmented plane wave method within the local density approximation, were carried out for the effect of pressure on the electronic and optical properties of the filled tetrahedral compounds LiMgN, LiMgP and LiMgAs. The bandgap pressure coefficient trend in the ternaries is found to be similar to the one encountered in the zinc-blende-like AlX. The first order bandgap pressure coefficient aΓ–ΓaΓ–Γ in LiMgN is larger than the corresponding one in AlN, while it is smaller in LiMgP and LiMgAs compared to the one in AlP and AlAs. The predicted values of the dielectric constants for LiMgN, LiMgP and LiMgAs are close to those of the binary compounds AlN, AlP and AlAs.