Dynamical atomic charges: The case of ABO(3) compounds

摘要: Based on recent first-principles computations in perovskite compounds, especially BaTiO3, we examine the significance of Born effective charge concept and contrast it with other atomic definitions, either static (Mulliken, Bader, etc.) or dynamical (Callen, Szigeti, etc.). It is shown that charges are not driven by same underlying parameters. A unified treatment periodic solids large clusters proposed. The origin difference between discussed terms local polarizability delocalized transfers charge: models succeed reproducing anomalous thanks to polarizabilities but, ABO(3) ab initio calculations favor physical picture based upon transfer charges. Various results concerning barium strontium titanates presented. a band-by-band decomposition which allows us identify displacement Wannier center separated bands induced an displacement. sensitivity microscopic macroscopic strains examined. Finally, estimate spontaneous polarization four phases titanate.