The atomic interactions and anharmonicity of atomic displacements in the virtual ferroelectric KTaO3, potassium tantalate, have been studied using accurate single-crystal X-ray diffraction at room temperature. The multipole analysis of electron density and Gram–Charlier series description of anharmonic atomic displacements allowed us to perform a quantitative analysis of the chemical bonding and atomic motion in this crystal. Closed-shell interactions between Ta—O and K—O pairs of atoms were found, while no interaction was observed for the Ta—K and O—O atomic pairs. The character of the anharmonic atomic displacements is discussed and compared with those in SrTiO3.
