Structural, electronic, optical and thermodynamical properties of Cu3Se2 and [Cu3Se2]:Zn compounds: Using DFT

We have studied theoretically the structural, electronic, optical and thermodynamical properties of Cu3Se2 and Zn-doped Cu3Se2 under first principles of DFT calculations by using computer code Wien-2K. First, the unit cell volume was minimized and investigations were carried out in all these properties on LDA, GGA, and mBJ potentials. It was observed that, for Cu3Se2, the main contribution is due to Cu-d and Se-p in valence band and Se-p and Se-d in the conduction band while for [Cu3Se2]: Zn the contribution in valence band is mainly due to the Se-3p and Zn-3d and for conduction band, it is due to the Cu-s and Zn-d orbitals. From calculations, it is also observed that the Cu3Se2 shows metallic nature but after doping Zn it shows semiconducting nature of about 0.6eV, which is the confirmation of the metallic and semiconductor behavior of both the compounds respectively. It means with the doping of Zn, the material shifted from metal to semiconductor. We also investigated reflectivity, refractive index, energy loss, and absorption of Cu3Se2 and [Cu3Se2]: Zn. The thermodynamical properties of Cu3Se2 and [Cu3Se2]:Zn compounds are studied by using semi-classic Boltzmann transport theory implemented in Wien-2k computer code by which we investigated specific heat capacity at constant volume (Cv), specific heat capacity at constant pressure (C-p), the expansion coefficient (alpha), Debye temperature (theta(D)), Gruneisen parameter (gamma), and variation in volume against the temperature.