First-Principles Calculations to Investigate Structural, Electronic, Optical, and Elastic Properties of Ceria

Abstract

The structural, electronic, optical, and elastic properties of Ceria (CeO2) were investigated using local density approximation (LDA), PBE, DFT + U, and PBE0 approximations. In all approximations, the convergence test of total energy with respect to kinetic energy cutoff, k-point, and lattice constant of CeO2 was performed consequently to increase the accuracy of computations. The O (2p)-Ce (4f) bandgap of CeO2 calculated using DFT + U (3.0 eV) is consistent with experimentally reported value (3.0–3.33 eV) than with LDA (2.2 eV), PBE (2.5 eV), and PBE0 (4.47 eV). Both LDA and PBE underestimated the bandgap of CeO2 while the PBE0 overestimated the bandgap of CeO2 as compared to the experimental value. The optical properties such as the imaginary part of the dielectric function (ε2), extinction coefficient (k), and refractive index (n) of ceria obtained using the three approaches are also consistent with the available theoretical and experimental data. In addition, the maximum peak for absorption coefficient was found at about 13 eV for (LDA and PBE) and around 11 eV for DFT + U calculations. Furthermore, the analyses of optical properties support the electronic properties of ceria. The elastic properties such as bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, Debye temperature, and Debye sound velocity were computed to investigate the mechanical properties of CeO2 and compared with the experimental and theoretical results. The result of elastic parameters found confirms that CeO2 is mechanically stable and has potential for a variety of different electronic applications.