First principles investigations on elastic and electronic properties of BaHfN2 under pressure

We investigate the elastic and electronic structure properties of BaHfN2 under pressure by performing the generalized gradient approximation (GGA) and local density approximation (LDA) correction scheme in the frame of density functional theory (DFT). The pressure dependences of the normalized lattice parameters a/a(0) and c/c(0), the ratio c/a, and the normalized primitive volume V/V-0 of BaHfN2 are also obtained. The obtained lattice constants and bulk modulus agree well with the available experimental and other theoretical data. The pressure dependences of elastic properties are investigated for the first time. It is found that, as the pressure increases, the elastic constants C-11, C-33, C-66, C-12 and C-13 increase, the variation of elastic constant C-44 is not obvious. At 40 GPa, the tetragonal structure BaHfN2 transfers to another structure at zero temperature. Moreover, our compressional and shear wave velocities V-L = 5.87 km/s and V-S = 3.12 km/s as well as the Debye temperature Theta = 451.7 K at 0 GPa are obtained. The pressure dependences of the band structures, energy gap and density of states are also investigated. (C) 2012 Elsevier B. V. All rights reserved.