Comparative study of the effect of the Hubbard coefficient U on the properties of TiO2 and ZnO

A.C. ROSSI FERN´ANDEZ A, A.B. SCHVVAL A, M.J. JIM´ENEZ A, G.F. CABEZA A, C.I.N. MORGADE

Materials Today Communications

elsevier

Año: 2021 p. 1 - 12

2352-4928

First-principles calculations combined with Hubbard U correction based on Density Functional Theory has beenused to investigate the effect of its inclusion on electronic, structural, and optical properties and to reproducecorrect band gap for TiO2 (anatase and rutile) and ZnO (wurtzite) structures. The effect of the implementation ofU for only metal (Ti or Zn) d state (Ud) or for both 3d (Ud) and Op (Up) states was investigated to exploringchanges in valence and conduction bands and their origin. Bader?s charge analysis has been used to revealing thenature of chemical bonding. We can conclude that for both TiO2 polymorphs as the Ud factor increases, both theBG and the lattice parameter increase. On the contrary, for ZnO, as Ud increases the value of BG increases but thecell parameter decreases. The optimal values correspond to Ud =8 eV (TiO2) and Ud =13 eV (ZnO). The correspondingoptical properties using Ud, such as real and imaginary parts of dielectric function, reflectivity R(ω),refractive index n(ω), extinction coefficient k(ω), absorption coefficient α(ω) and electron energy loss function L(ω) has been calculated. It is important to highlight that the curves obtained considering the inclusion of the Udshow an excellent agreement with those reported experimentally.