Consistent Atomic Geometries and Electronic Structure of Five Phases of Potassium Niobate from Density-Functional Theory. (30th January 2017)

• Record Type: Journal Article
• Authors: Schmidt, Falko; Landmann, Marc; Rauls, Eva; Argiolas, Nicola; Sanna, Simone; Schmidt, W. G.; Schindlmayr, Arno
• Other Names: Roussel Pascal Academic Editor.
• Is Part Of: Advances in materials science and engineering. Volume 2017(2017)
• Publication Date: 2017-01-30
• Subjects: Materials science -- Periodicals; Materials science; Periodicals; 620.11
• DOI: 10.1155/2017/3981317
• Languages: English
• ISSNs: 1687-8434

Abstract

Abstract : We perform a comprehensive theoretical study of the structural and electronic properties of potassium niobate (K N b O 3 ) in the cubic, tetragonal, orthorhombic, monoclinic, and rhombohedral phase, based on density-functional theory. The influence of different parametrizations of the exchange-correlation functional on the investigated properties is analyzed in detail, and the results are compared to available experimental data. We argue that the PBEsol and AM05 generalized gradient approximations as well as the RTPSS meta-generalized gradient approximation yield consistently accurate structural data for both the external and internal degrees of freedom and are overall superior to the local-density approximation or other conventional generalized gradient approximations for the structural characterization of K N b O 3 . Band-structure calculations using a HSE-type hybrid functional further indicate significant near degeneracies of band-edge states in all phases which are expected to be relevant for the optical response of the material.