GW-BSE Calculations of Electronic Band Gap and Optical Spectrum of ZnFe

Autor: Anna C, Ulpe, Thomas, Bredow
Rok vydání: 2019
Předmět:
Zdroj: Chemphyschem
ISSN: 1439-7641
Popis: The G0W0, evGW0, evGW, and scGW0 approximations to many‐body perturbation theory combined with the Bethe‐Salpeter approach (BSE) are applied to calculate electronic and optical properties of the open‐shell spinel ferrite ZnFe2O4. The effect of the various degrees of self‐consistency is assessed by comparison to recent experimental results. Furthermore, the influence of the method for obtaining the ground‐state wavefunction is studied, including the GGA functional PBE with and without an intermediate step using the COHSEX approximation, as well as PBE+U, where we try to minimize the influence of the Hubbard potential U. Best agreement for the optical band gap and the first maxima of the excitation spectrum is obtained with the evGW method based on a PBE+U wavefunction. This method is chosen and converged carefully to yield quantitative results for the optical spectra of four different magnetic structures and cation distributions of ZnFe2O4. With the results we provide a possible explanation for inconsistency in experimental results.
A theoretical approach is developed to obtain qualitative information on the optical properties of the spinel zinc ferrite ZnFe2O4. The calculations reveal a pronounced dependency of the optical spectrum of ZnFe2O4 on the cation and magnetic state.
Databáze: OpenAIRE
Externí odkaz: