First-principles calculation of the electronic and optical properties of Gd2FeCrO6 double perovskite: Effect of Hubbard U parameter

We have synthesized Gd2FeCrO6 (GFCO) double perovskite which crystallized in monoclinic structure with P2(1)/n space group. The UV-visible and photoluminescence spectroscopic analyses confirmed its direct band gap semiconducting nature. Here, by employing experimentally obtained structural parameters in first-principles calculation, we have reported the spin-polarized electronic band structure, charge carrier effective masses, density of states, electronic charge density distribution and optical absorption property of GFCO double perovskite. Moreover, the effects of on-site d-d Coulomb interaction energy (U-eff) on the electronic and optical properties were investigated by applying a range of Hubbard U-eff parameter from 0 to 6 eV to the Fe-3d and Cr-3d orbitals within the generalized gradient approximation (GGA) and GGA thorn U methods. Notably, when we applied U-eff in the range of 1-5 eV, both the up-spin and down-spin band structures were observed to be direct. The charge carrier effective masses were also found to enhance gradually from U-eff 1/4 1 eV-5 eV, however, these values were anomalous for U-eff 1/4 0 and 6 eV. These results suggest that U-eff should be limited within the range of 1-5 eV to calculate the structural, electronic and optical properties of GFCO double perovskite. Finally we observed that considering U-eff 1/4 3 eV, the theoretically calculated optical band gap-1.99 eV matched well with the experimentally obtained value similar to 2.0 eV. The outcomes of our finding imply that the U-eff value of 3 eV most accurately localized the Fe-3d and Cr-3d orbitals of GFCO keeping the effect of self-interaction error from the other orbitals almost negligible. Therefore, we may recommend U-eff 1/4 3 eV for first-principles calculation of the electronic and optical properties of GFCO double perovskite that might have potential in photocatalytic and related solar energy applications. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

In this study, Gd2FeCrO6 (GFCO) double perovskite was synthesized and its structural and optical properties were investigated. The results suggest that the U-eff value should be limited within the range of 1-5 eV for accurate calculations. When U-eff is set at 3 eV, the theoretically calculated optical band gap closely matched the experimental value.