First principles calculations of the structural and elastic properties of the filled tetrahedral compounds LiCdX (X = N, P, As)

We have investigated the structural and elastic properties of the Nowotny–Juza filled tetrahedral compounds LiCdX (X = N, P, As) by using the full-potential linearized augmented plane wave method within the local density approximation. The α-phase for the studied materials, which is energetically favourable than the β one, is softer than the binary analogous compounds; InN, InP and InAs. The calculated sound speeds are quantitatively similar for the ternaries and their binary analogous compounds. These results are confirmed by the data obtained from the phonon spectra for LiCdP and LiCdAs, using the plane wave pseudopotential method.