Elastic constants and Debye temperature of wz-AlN and wz-GaN semiconductors under high pressure from first-principles

First-principles calculations were performed to study the elastic stiffness constants (C _ij ) and Debye temperature (?? _D) of wurzite (wz) AlN and GaN binary semiconductors at high pressure. The lattice constants were calculated from the optimized structure of these materials. The band gaps were calculated at Γ point using local density approximation (LDA) approach. The unit cell volume, lattice parameters, c/a, internal parameter (u), elastic constant (C _ij ), Debye temperature (?? _D), Hubbard parameter (U) and band gap (E _g) were studied under different pressures. The bulk modulus (B ₀), reduced bulk modulus ( (B_{0}^{prime })) and Poisson ratio (υ) were also calculated. The calculated values of these parameters are in fair agreement with the available experimental and reported values.