Short-circuit boundary conditions in ferroelectric PbTiO3 thin films:: Density-functional theory calculations

We examine the application of short-circuit electrical boundary conditions in density-functional theory calculations of ferroelectric thin films. Modeling PbTiO3 films with Pt electrodes, we demonstrate that under periodic boundary conditions of supercells, short-circuit conditions for the electrodes are equivalently satisfied in two repeated slab geometries: a PbTiO3/metal superlattice geometry and a periodic metal/PbTiO3/metal/vacuum geometry, where the metal is Pt or SrRuO3. We discuss the benefits of each geometry in the study of ferroelectricity in thin films.