DEFORMATION ELECTRON-DENSITY ANALYSIS OF NANO2 AT 30 K

Hirshfeld multipole deformation density analysis of ferroelectric NaNO 2 has been performed using X-ray data taken at 30 K. A perfect converg ence of least-square refinement has not been attained due to the stron g correlation between odd multipole terms. However, reliable results c ould be obtained under the imposed constraints, with reasonable discre pancy factors and the deformation densities. The net charges for Na, N and O atoms were estimated to be 0.27, 0.20 and -0.24, respectively. The spontaneous polarization value was calculated using these net char ges and atomic dipole terms. It is shown that the calculated values (7 .3 or 16 mu C/cm(2), depending on the way of calculation) are much clo ser to the observed value (11.9 mu C/cm(2)) compared to the calculated value from formal point charge (74 mu C/cm(2)).