Open AccessQuasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4
Author(s) -
Sergej Neufeld,
Arno Schindlmayr,
Wolf Gero Schmidt
Publication year - 2021
Publication title -
jphys materials
Language(s) - English
Resource type - Journals
ISSN - 2515-7639
DOI - 10.1088/2515-7639/ac3384
Subject(s) - quasiparticle , exciton , binding energy , gw approximation , perturbation theory (quantum mechanics) , density functional theory , atomic physics , physics , electronic band structure , dielectric , condensed matter physics , rubidium , absorption (acoustics) , chemistry , potassium , quantum mechanics , optics , superconductivity , organic chemistry
Many-body perturbation theory based on density-functional theory calculations is used to determine the quasiparticle band structures and the dielectric functions of the isomorphic ferroelectrics rubidium titanyl phosphate (RbTiOPO 4 ) and potassium titanyl arsenide (KTiOAsO 4 ). Self-energy corrections of more than 2 eV are found to widen the transport band gaps of both materials considerably to 5.3 and 5.2 eV, respectively. At the same time, both materials are characterized by strong exciton binding energies of 1.4 and 1.5 eV, respectively. The solution of the Bethe–Salpeter equation based on the quasiparticle energies results in onsets of the optical absorption within the range of the measured data.