A THEORETICAL STUDY OF ELASTIC, ELECTRONIC, OPTICAL AND THERMODYNAMIC PROPERTIES OF AlB2 AND TaB2

ABSTRACT Using ab-initio method we have studied the structural, elastic, electronic, optical and thermodynamic properties of AlB 2 and TaB 2 . We have used plane wave pseudopotential with generalised gradient approximation as implemented in CASTEP program. The independent elastic constants, bulk modulus, Young’s modulus, shear modulus, anisotropic factor, Pugh ratio, etc are calculated. This results show that AlB 2 and TaB 2 are mechanically stable. We have also calculated the band structure and density of states. Band structure results show that AlB 2 and TaB 2 show metallic behaviour. In order to understand the electronic properties in a better way we have also calculated dielectric function, refractive index, absorption coefficient, conductivity, loss function and reflectivity. Results of absorption coefficient and conductivity are in good agreement with the band structure results. The effect of temperature and pressure on the bulk modulus, Debye temperature, specific heat and also on the thermal expansion coefficient are derived from the quasi-harmonic Debye model with phononic effect in both cases.The results for the elastic and electronic properties are compared to experimental measurements and with the results obtained in different band-structure calculations, however, no optical data are available for comparison.