Regensburg 2016 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 11: Poster

DF 11.26: Poster

Wednesday, March 9, 2016, 18:00–20:00, Poster E

Zero-point renormalization and temperature dependence of the LiNbO₃ band gap from first principles — •Michael Friedrich, Arthur Riefer, Simone Sanna, Wolf Gero Schmidt, and Arno Schindlmayr — Department Physik, Universität Paderborn, 33095 Paderborn, Germany

Lithium niobate (LiNbO₃, LN) is a dielectric crystal with outstanding electro-optical properties that is widely used for optical waveguides and other commercial applications. As previous experimental and theoretical studies have mostly concentrated on the ground-state properties, the variation of technologically important material parameters with the temperature, which stems from the coupling to phonons, has received little attention until now.

Here we perform quantitative calculations within density-functional perturbation theory as well as ab initio molecular dynamics in order to evaluate the vibrational contributions to the LN fundamental band gap. Our results indicate a large shift of 0.4 eV due to the zero-point renormalization and predict a temperature-dependent variation of the band gap that are both in excellent agreement with the available experimental data.

[1] M. Friedrich et al., J. Phys.: Condens. Matter 27, 385402 (2015).