Structural, Electronic, and Mechanical Properties of Anatase and Rutile Titanium Dioxide Phases using the Density Functional Theory

This study investigates the structural and electronic properties of the anatase and rutile TiO2 systems by employing the Quantum Espresso (QE) software using first-principles calculations based on Density Functional Theory (DFT). Optimized lattice constants (a = 3.788, 4.627 a.u. and c = 9.491, 2.979 a.u.) and the internal parameter u (0.209, 0.305), were obtained for anatase and rutile TiO2 phases, respectively. Unit cell volumes were also calculated. Furthermore, the Birch-Murnaghan equation of state was used to obtain the equilibrium volume (937.5, 428.3 a.u.3), the bulk modulus (198.5, 222.5 GPa), and the pressure derivative of the bulk modulus (4.18, 4.37) for both phases. The results are in good agreement with the experimental data and the theoretical results published in other studies. Finally, the energy band gap of both samples was calculated (1.8 and 1.6 eV, respectively) and compared with published results obtained from the Density Of Electron States (DOS).