title: Towards an accurate description of perovskite ferroelectrics: exchange and correlation effects.
abstract: Using the van der Waals density functional with C09 exchange (vdW-DF-C09), which has been applied to describing a wide range of dispersion-bound systems, we explore the physical properties of prototypical ABO3bulk ferroelectric oxides. Surprisingly, vdW-DF-C09 provides a superior description of experimental values for lattice constants, polarization and bulk moduli, exhibiting similar accuracy to the modified Perdew-Burke-Erzenhoff functional which was designed specifically for bulk solids (PBEsol). The relative performance of vdW-DF-C09 is strongly linked to the form of the exchange enhancement factor which, like PBEsol, tends to behave like the gradient expansion approximation for small reduced gradients. These results suggest the general-purpose nature of the class of vdW-DF functionals, with particular consequences for predicting material functionality across dense and sparse matter regimes.
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, 37831, TN, USA.
authors.forename: Simuck F
authors.initials: SF
authors.lastname: Yuk
authors.affiliation: Department of Materials Science & Engineering, and Institute of Materials Science, University of Connecticut, Storrs, 06269, Connecticut, USA.
authors.forename: Krishna Chaitanya
authors.initials: KC
authors.lastname: Pitike
authors.affiliation: Department of Materials Science & Engineering, and Institute of Materials Science, University of Connecticut, Storrs, 06269, Connecticut, USA.
authors.forename: Serge M
authors.initials: SM
authors.lastname: Nakhmanson
authors.affiliation: National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, 37831, TN, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Eisenbach
authors.affiliation: National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, 37831, TN, USA.
authors.forename: Ying Wai
authors.initials: YW
authors.lastname: Li
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, 37831, TN, USA. coopervr@ornl.gov.
authors.forename: Valentino R
authors.initials: VR
authors.lastname: Cooper