ELECTRON DEFORMATION DENSITY STUDIES OF PEROVSKITE COMPOUNDS

Experimental charge density studies are performed From combined X-ray and neutron diffraction experiments (mainly single-crystal sample with a four-circle diffractometer). Structure factors are generaly refined from X-ray diffraction using a least-squares pseudo-atom multipolar m odel, which supposes an aspherical electronic distribution around the nucleus. Deformation density maps allow to study the spatial distribut ion of the electrons involved in the chemical bonding. Deconvoluting t he structure factor from thermal motions, one obtains static density m aps, directly comparable to the ab-initio theoretical density maps. Th e use of multipolar models for refinements allow the determination of some important parameters such as d orbital population or effective el ectronic charge localised on every atoms. In this presentation, we rep ort some experimental and theoretical works which use the electron def ormation density method and lead to a better understanding of the chem ical bonds involved in perovskite-like compounds.