First-principles study of structural, elastic, electronic and thermodynamic properties of topological insulator Bi₂Se₃ under pressure

Abstract

The structural, elastic, electronic and thermodynamic properties of the rhombohedral topological insulator Bi₂Se₃ are investigated by the generalized gradient approximation (GGA) with the Wu–Cohen (WC) exchange-correlation functional. The calculated lattice constants agree well with the available experimental and other theoretical data. Our GGA calculations indicate that Bi₂Se₃ is a 3D topological insulator with a band gap of 0.287 eV, which are well consistent with the experimental value of 0.3 eV. 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 Bi₂Se₃ are also obtained successfully. The bulk modulus obtained from elastic constants is 53.5 GPa, which agrees well with the experimental value of 53 GPa. We also investigate the shear sound velocity V_S, longitudinal sound velocity V_L, and Debye temperature Θ_E from our elastic constants, 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 at 0 GPa and 300 K are 120.78 J mol⁻¹ K⁻¹ and 4.70 × 10⁻⁵ K⁻¹, respectively.

Keywords:

• Density functional theory
• elastic properties
• electronic properties
• thermodynamic properties
• Bi₂Se₃

Acknowledgements

The authors acknowledge the support for the computational resources by the State Key Laboratory of Polymer Materials Engineering of China in Sichuan University.

Disclosure statement

No potential conflict of interest was reported by the authors.