Prediction study of structural and elastic properties under the pressure effect of M2GaC (M=Ti,V,Nb,Ta)

Using first-principles density functional calculations, the effect of high pressures, up to 20 GPa, on the structural and elastic properties of M2GaC, with M=Ti, V, Nb, and Ta, were studied by means of the pseudopotential plane-waves method. Calculations were performed within the local density approximation to the exchange-correlation approximation energy. The lattice constants and the internal parameters are in agreement with the available results. The elastic constants and their pressure dependence are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young's moduli, and Poisson's ratio for ideal polycrystalline M2GaC aggregates. We estimated the Debye temperature of M2GaC from the average sound velocity. This is a quantitative theoretical prediction of the elastic properties of Ti2GaC, V2GaC, Nb2GaC, and Ta2GaC compounds and it still awaits experimental confirmation. (c) 2007 American Institute of Physics.