Regensburg 2019 – wissenschaftliches Programm
KFM 14.21: Poster
Mittwoch, 3. April 2019, 16:00–18:30, Poster C
Quasi particle energies and optical properties of KTiOPO4 calculated by first principles — •Sergej Neufeld, Adriana Bocchini, Uwe Gerstmann, Arno Schindlmayr, and Wolf Gero Schmidt — Universität Paderborn
Potassium titanyl phosphate (KTiOPO4, KTP) is a ferroelectric material that has been utilized in numerous applications based on non linear optics and photonics.
Despite its widespread use, many KPT properties are insufficiently understood. This concerns, e.g. its band gap. Earlier theoretical studies are based on the single-particle picture and report values between 3.0 - 4.0 eV.
In this work, quasiparticle and excitonic effects on the band structure and dielectric function of stoichiometric KTP are studies within the GW0 approximation and by solving the Bethe Salpeter equation (BSE), respectively. It is found that quasiparticle effects open up the band gap to about 5.3 eV. The solution of the BSE yields exciton binding energies of the order of 1.5 eV. Calculations that include both quasiparticle and excitonic effects are found to account for the measured reflectivity.