Density Functional Theory Analysis on the Structural Properties of Cubic and Monoclinic Tungsten Trioxide

Abstract

Tungsten trioxide (WO₃) is a transitional product in the recovery of tungsten from its minerals. Recently, it has shown a growing attention both within the theoretical and experimental research due to its special structural properties and its high potential in electronic applications. The crystal lattice of tungsten trioxide is highly dependent on temperature. In this work we investigated the equilibrium structure of tungsten trioxide in two crystal systems, i.e. monoclinic and cubic systems. We carried out our first principle calculations using a pseudo potential method based on the density functional theory (DFT) with generalized gradient approximation (GGA) as exchange correlation energy as implemented in Quantum ESPRESSO code. In each case, we calculated total energy, Fermi energy, density of states and then we made comparisons. The results show that WO₃ is a semiconductor in all two crystal structures with zero total magnetization. Moreover, tungsten trioxide has a direct band gap with a gap value of about 1.02eV for cubic and indirect band gap with value of about 0.98eV for monoclinic which are all in the range of visible wavelength that improves its optical applications potentially.