First-principles investigations on elastic, phonon and thermodynamic properties of SrB6 under pressure

Abstract: The elastic, phonon and thermodynamic properties of the divalent alkaline-earth hexaboride SrB6 are investigated by using plane-wave pseudopotential density functional theory method. The calculated structure parameters and bulk modulus are well consistent with the available experiment and theoretical data. The pressure dependences of elastic constants C ij , bulk modulus B 0, shear modulus G, Young''s modulus E and Poisson''s ratio σ are also presented. With these elastic parameters, we investigate the mechanical stability and compressibility of SrB6. For the thermodynamic properties, both phonon and quasi-harmonic Debye model methods are adopted. Through the comparison with experimental and other theoretical results, we found the method of quasi-harmonic Debye model is a little better. Moreover, the phonon dispersion relations are also obtained. It is found that there are two LO/TO splitting around 5THz and 26THz, respectively. [Copyright &y& Elsevier]