Investigation of self-consistent site-dependent DFT + U effect on electronic band structure and optical properties of SiFe2O4 spinel

Abstract

The first-principle investigation of SiFe _2 O _4 (SFO) spinel was performed with the help of a plane-wave pseudopotential technique within the generalized gradient approximation (GGA) and local density approximation (LDA) as implemented in Quantum Espresso Simulation package. The Electronic band structure and optical properties of SFO spinel-type material have been investigated and discussed in this paper. The calculated band structure reveals that SFO spinel-type material is a direct bandgap semiconductor. Using GGA + U and LDA + U the band gap value so obtained is 3.52 eV and 2.96 eV respectively. The contribution to valence and conduction bands due to different bands was analyzed on the basis of the total and partial density of state. The Optical properties of SFO spinel-type material have been calculated and discussed in detail. The real, ${\varepsilon }_{1}\left(\omega \right)$ and the imaginary, ${\varepsilon }_{2}\left(\omega \right)$ part of the complex dielectric constants is found to be 6.52 and 5.42 at energies of 3.44 eV and 6.21 eV respectively. The refractive index $n\left(0\right)$ and the reflectivity index $({\rm{R}}\left({\rm{\omega }}\right)),$ at zero energy value were found to be 1.88 and 10% respectively. We found that SFO spinel-type material has good properties for optical devices.

Keywords

• optoelectronics properties
• SiFe2O4 spinel
• DFT + U
• dielectric constants
• random phase approximation