Ab initio calculations of structural, phase transition, phonon and thermodynamic properties of AlAs

This paper is an attempt to investigate the structural properties, phase transition, and thermodynamic and phonon properties of AlAs. Quasi-harmonic Debye- Einstein model was used to obtain lattice constant and static Bulk modulus B0 for B3, B8 and B1phases. These results showed good consistency with experimental results and other theoretical data. Afterwards, the phase transitions of B3 to B1 and B3 to B8 obtained were equal to 7.9 GPa and 11.2 GPa respectively, which also indicated a good consistency with the theoretical and experimental results. In addition, phonon properties of B3 phase were compared with experimental data, and the results demonstrated a good consistency with experimental results especially in the gamma point that is the basis of thermodynamic calculations. Furthermore, the diagrams of heat capacity at constant volume and heat capacity at constant pressure were investigated in terms of temperature for B3 phase, and the results showed their significant consistency with theoretical and experimental results.