First-principles study of structural, elastic, electronic and thermodynamic properties of topological insulator Sb2Te3 under pressure
2015
Abstract The structural, elastic, electronic and thermodynamic properties of the rhombohedral topological insulator Sb 2 Te 3 ( α -Sb 2 Te 3 ) are investigated by the generalized gradient approximation (GGA) with the PBESOL exchange–correlation functional in the framework of density-functional theory. The calculated lattice parameters of Sb 2 Te 3 at the ground state are in good agreement with the available experimental data and better than other calculated results. The pressure dependence of the elastic constants C ij , bulk modulus B , shear modulus G , Young’s modulus E , and Poisson’s ratio σ of Sb 2 Te 3 are also obtained successfully. The obtained density of states, charge density difference and total charge density show that Sb–Te bonds have some covalent features at the ground state. Finally, we investigate the shear sound velocity V S , longitudinal sound velocity V L , and Debye temperature Θ E from our elastic constants of Sb 2 Te 3 , as well as the thermodynamic properties from quasi-harmonic Debye model. We obtain that the heat capacity C v and the thermal expansion coefficient α of Sb 2 Te 3 at 0 GPa and 300 K are 120.79 J mol −1 K −1 and 5.19 × 10 −5 K −1 , respectively.
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