A DFT study about the effects of exchange-correlation functional on the structural and electronic properties of Anatase

Abstract

A comparative study is presented, based on Density Functional Theory, of the influence that the different approximations of the exchange-correlation functional have on the structural and electronic properties of titanium dioxide in the anatase phase. In this work, the method of plane waves and pseudopotentials, as implemented in the Quantum Espresso package was used. The approximations to the correlation-exchange functional that were considered are the local density approximation, the generalized gradient approximation in the form of Perdew-Burke-Ernzerhof, the Perdew-Burke-Ernzerhof for solids, and the Perdew-Wang 91. For each case, the effects due to the inclusion of spin (spin polarization), and the correction of Hubbard (U=4.2 eV for Ti) were also studied. We found that the Perdew-Burke-Ernzerhof for solids functional offers the best results for the calculation of the lattice parameters and bond lengths, followed by the local density approximation with the Hubbard correction included. For the bond angles, the best description was obtained with the local density approximation. The inclusion of the U term increases the errors associated with the mentioned structural parameters when the following functionals are used: Perdew-Burke-Ernzerhof, Perdew-Burke-Ernzerhof for solids and Perdew-Wang 91. The Perdew-Burke-Ernzerhof and Perdew-Wang 91 functionals show the largest errors when the Hubbard correction is used; while the local density approximation shows significant improvement when the Hubbard correction is included. Regarding the energy gap, we found that the introduction of the U term improves the estimation of this property for all the approximations included in this work.

Understanding the prototype catalyst TiO2 surface with the help of density functional theory calculation

“…Different U values can be observed if properties other than the electronic band gap, such as relative energetic ordering and reaction energy, are taken into account. Actually, Hubbard corrections with U d = 4.2 eV are widely used for TiO 2 calculations, 17 and they are a suitable compromise between the band gap and other physical properties.…”

“…Ramirez et al investigated the influence of different exchange‐correlation functionals, including PBE, PBES, PW91, and LDA, on the structural and electronic properties of anatase TiO 2 17 . The Hubbard corrections with U d = 4.2 eV were also considered.…”

“…Ramirez et al investigated the influence of different exchange-correlation functionals, including PBE, PBES, PW91, and LDA, on the structural and electronic properties of anatase TiO 2 . 17 The Hubbard corrections with U d = 4.2 eV were also considered. It was found that PBES gives the best results for the lattice parameters and bond lengths, followed by LDA + U, while LDA gives the best bond angles.…”

Exploration of the physical properties of the newly synthesized kagome superconductor LaIr3Ga2 using different exchange–correlation functionals

“…It is worth mentioning that GGA sometimes slightly overestimates the lattice constants. 44,50 Although it is computationally expensive, HSE06 (usually used for semiconductors) is beneficial for estimating the dielectric function because it produces band gaps closer to the experimental values 37 than those obtained via GGA or LDA. Table 1 shows the results of lattice constants a, c, and c/a ratio for the various exchange-correlation functionals with experimentally reported data.…”

“…Some exchange-correlation functionals underestimate the lattice constant, while others overestimate the lattice constant. [43][44][45] For a particular structure, a larger lattice constant (volume) results in smaller elastic moduli (due to the lower strength of atomic bonds). In contrast, a smaller lattice constant (volume) results in higher elastic moduli (due to higher bonding strength).…”