ChemInform Abstract: DEFORMATION ELECTRON DENSITY OF α-GLYCYLGLYCINE AT 82 K. II. THE X-RAY DIFFRACTION STUDY

1979 ◽  
Vol 10 (48) ◽  
Author(s):  
A. KVICK ◽  
T. F. KOETZLE ◽  
E. D. STEVENS
Keyword(s):  
Diffraction Study ◽  
Electron Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Deformation Electron Density

X-ray diffraction study of the atomic interactions, anharmonic displacements and inner-crystal field in orthorhombic KNbO3

2021 ◽  
Vol 77 (5) ◽  
Author(s):  
Adam I. Stash ◽  
Ekaterina O. Terekhova ◽  
Sergey A. Ivanov ◽  
Vladimir G. Tsirelson
Keyword(s):  
Diffraction Study ◽  
Electron Density ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Structural Disorder ◽  
Space Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Vibrations

An X-ray diffraction study aimed at establishing the subtle details of the electron density and anharmonicity of the atomic vibrations in a stoichiometric monodomain single crystal of potassium niobate, KNbO3, has been conducted at room temperature (orthorhombic ferroelectric phase Amm2). The cation and anion displacements obtained from the experiment are weakly anharmonic without any manifestation of structural disorder. The chemical bond and interatomic interactions inside and between crystal substructures at the balance of intracrystalline forces are characterized in detail. The role of each of the ions in the formation of the ferroelectric phase was studied and the features of the electron-density deformation in the niobium and oxygen substructures, and the role of each of them in the occurrence of spontaneous polarization are established. The position-space distribution of electrostatic and quantum forces in KNbO3 is restored. It is emphasized that for the completeness of the analysis of the nature of the ferroelectric properties it is necessary to consider both static and kinetic electronic factors, which are of a quantum origin. The experimental results and theoretical estimations by the Kohn–Sham calculation with periodic boundary conditions are in reasonable agreement, thus indicating the physical significance of the findings of this study.

Electron density in the sodium vanadium oxide bronze β-Na x V2O5 at 9 K

2001 ◽  
Vol 57 (3) ◽  
pp. 244-250 ◽  
Author(s):  
Ruslan P. Ozerov ◽  
Victor A. Streltsov ◽  
Alexander N. Sobolev ◽  
Brian N. Figgis ◽  
Victor L. Volkov
Keyword(s):  
Vanadium Oxide ◽  
Electron Density ◽  
Room Temperature ◽  
Temperature Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Valence States ◽  
Vanadium Oxide Bronze ◽  
Oxide Bronze ◽  
Deformation Electron Density

The crystal structure and electron density in sodium vanadium oxide bronze, β-Na x V2O5 [x = 0.282 (3)], have been studied by accurate Mo Kα X-ray diffraction measurements at 9.6 (3) K. No noticeable difference in the crystal structures at room temperature and 9.6 K has been observed. No superstructure reflections, previously found by Kanai, Kagoshima & Nagasawa [(1982), J. Phys. Soc. Jpn, 51, 697–698], have been detected at low temperature. Analysis of the deformation electron density has revealed the presence of the quasi-two-dimensional sheets of the —V—O—V—O— bonds in the structure. The electron density in the different chemical bonds within each of the three crystallographically independent VO6 polyhedra noticeably varies, although there is no clear evidence that the three crystallographically independent V atoms have different valence states.

Electron Density and Anharmonic Thermal Atomic Vibrations in K1_ xLixTaO3 (x=0, 0.05, 0.15) Perovskites

1993 ◽  
Vol 48 (1-2) ◽  
pp. 25-28 ◽  
Author(s):  
E. A. Zhurova ◽  
V. E. Zavodnik ◽  
S. A. Ivanov ◽  
P. P. Syrnikov ◽  
V. G. Tsirelson
Keyword(s):  
Electron Density ◽  
Thermal Motion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Maps ◽  
Atomic Vibrations ◽  
Deformation Electron Density ◽  
Oxygen Atoms

Abstract The results of accurate X-ray diffraction studies of KTaO3 , K0,95Li0,05TaO3 and K0,85Li0,15TaO3 crystals are presented. Anharmonicity of the thermal motion of the oxygen atoms and deformation electron density maps are discussed.

scholarly journals Charge Density Study on Bullvalene (C10H10 )

1993 ◽  
Vol 48 (1-2) ◽  
pp. 55-57
Author(s):  
T. Koritsánszky ◽  
J. Buschmann ◽  
P. Luger
Keyword(s):  
Electron Density ◽  
Mean Square Displacement ◽  
Body Motion ◽  
X Ray Diffraction ◽  
Neutron Data ◽  
X Ray ◽  
Density Maps ◽  
Anisotropic Displacement Parameters ◽  
Deformation Electron Density ◽  
Density Study

Abstract Low-temperature single-crystal neutron and X-ray diffraction data were collected for bullvalene (Figure 1). X -N Fourier and multipole static deformation electron density maps were calculated and compared. Atomic mean-square-displacement parameters were analysed in the framework of the rigid-body motion model and the residual amplitudes (UOBS - UTLS) were graphically interpreted. The preliminary results presented here reveal either a bias in the X-ray anisotropic displacement parameters (ADPs) due to improper modelling of the electron density or unresolved errors in the neutron data.

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