First-principles high-throughput discovery of charge ordered ferroelectrics

Charge ordered ferroelectricity arises from the combination of a non polar structural distortion and a charge density wave ordering. Despite considerable fundamental and technological interest on charge ordered ferroelectrics, only a relatively small number of examples are known, and therefore, there is limited understanding of their properties and functionalities. In this work, we use first principles calculations to perform a high throughput search of new charge ordered ferroelectrics in the Materials Project database. We use relevant symmetry and physical descriptors such as polar space groups, positive band gap, multiple valence ions, local symmetries among metal sites, and energy above hull to select 80 candidate charge ordered ferroelectrics. Subsequently, we use first principles calculations to investigate the polarization switching and charge ordering states of selected promising cases. We discuss several challenges for high-throughput search of charge ordered ferroelectrics such as the choice of functional, the description of localized electronic states, and electron-lattice coupling. We use ab-initio calculations to compute the valence states of materials and extend the bond valence sum method implemented in Materials Project to a larger set of transition metals. This work is supported by ANID FONDECYT Regular 1220986.