Elektronenkorrelationseffekte in der Elektronendichteverteilung von Stickstoff und Acetylen / Effects of Electron Correlation in the Electron Density Distribution of Nitrogen and Acetylene

1978 ◽  
Vol 33 (2) ◽  
pp. 245-246
Author(s):  
Hans-Lothar Hase ◽  
Karl-Wilhelm Schulte ◽  
Armin Schweig
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Correlation ◽  
Electron Density Distribution ◽  
Electron Distribution ◽  
Lone Pair ◽  
General Interest ◽  
Atomic Core ◽  
Difference Density ◽  
Ci Calculations

It is shown by AHF-CI calculations that the changes in the electron distribution in bonding and lone pair regions of nitrogen and acetylene due to electron correlation can be neglected when calculating electron difference densities of these molecules. The changes brought about by electron correlation are such that the electron density in interatomic regions is reduced and in atomic (core) regions increased. These results might meet general interest in the area of electron difference density determinations.

scholarly journals Die zeitliche Änderung der radialen Elektronendichteverteilung beim Theta-Pinch

1963 ◽  
Vol 18 (8-9) ◽  
pp. 895-900
Author(s):  
Franz Peter Küpper
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Electron Distribution ◽  
Radial Symmetry ◽  
Zero Order ◽  
Time Interval ◽  
Interferometric Method ◽  
Density Distributions ◽  
Theta Pinch

In a θ-pinch the radial symmetry of the electron density distribution as a function of time has been measured by a MACH—ZEHNDER interferometer. In a time interval of 400 nsec during a discharge an image converter made three pictures (exposure times of 10 nsec each) . Up to 100 nsec after the first compression, the experimental results show different density distributions for the cases of trapped parallel and antiparallel magnetic fields. Complete radial symmetry of the electron density distribution was not found.Another interferometric method for measuring the radial symmetry of the electron distribution by observing “zero order” fringes is described.

scholarly journals Relativistic Hirshfeld atom refinement of an organo-gold(I) compound

IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Sylwia Pawlędzio ◽  
Maura Malinska ◽  
Magdalena Woińska ◽  
Jakub Wojciechowski ◽  
Lorraine Andrade Malaspina ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Correlation ◽  
Electron Density Distribution ◽  
Gold Atom ◽  
Relativistic Effects ◽  
Model Parameters ◽  
Statistical Parameters ◽  
Mercury Compounds ◽  
The Core

The main goal of this study is the validation of relativistic Hirshfeld atom refinement (HAR) as implemented in Tonto for high-resolution X-ray diffraction datasets of an organo-gold(I) compound. The influence of the relativistic effects on statistical parameters, geometries and electron density properties was analyzed and compared with the influence of electron correlation and anharmonic atomic motions. Recent work in this field has indicated the importance of relativistic effects in the static electron density distribution of organo-mercury compounds. This study confirms that differences in electron density due to relativistic effects are also of significant magnitude for organo-gold compounds. Relativistic effects dominate not only the core region of the gold atom, but also influence the electron density in the valence and bonding region, which has measurable consequences for the HAR refinement model parameters. To study the effects of anharmonic motion on the electron density distribution, dynamic electron density difference maps were constructed. Unlike relativistic and electron correlation effects, the effects of anharmonic nuclear motion are mostly observed in the core area of the gold atom.

scholarly journals Validation of experimental charge densities: refinement of the macrolide antibiotic roxithromycin

2010 ◽  
Vol 66 (5) ◽  
pp. 568-577 ◽  
Author(s):  
J. J. Holstein ◽  
P. Luger ◽  
R. Kalinowski ◽  
S. Mebs ◽  
C. Paulman ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Organic Molecules ◽  
Macrolide Antibiotic ◽  
Charge Densities ◽  
Atomic Properties ◽  
Difference Density ◽  
Multipole Refinement ◽  
Experimental Electron Density

Multipole refinements of larger organic molecules have so far been limited to a few exceptional cases. We report an investigation of the detailed experimental electron-density distribution (EDD) of roxithromycin, a macrolide antibiotic consisting of 134 atoms. Although the experimental multipole refinement on high-resolution synchrotron data converged smoothly, validation of the electron density by calculation of an `experiment minus invariom' difference density revealed conformational disorder of the H atoms. Hydrogen disorder is shown to affect the EDD, the electrostatic potential and atomic properties as defined by Bader's quantum theory of atoms in molecules. A procedure to obtain the electron density distribution in the presence of disorder is proposed.

Spatial Electron Density Distribution of Chlorine Atoms in Molecules of the Series 4-XC6H4MCCl2C(O)C6H5 (M = S and Se)

1994 ◽  
Vol 49 (3) ◽  
pp. 522-524
Author(s):  
Valentin P. Feshin ◽  
Yurii E. Sapozhnikov ◽  
Vasilii V. Shchepin ◽  
Irina Yu. Petukhova ◽  
Arsenii D. Gordeev ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Axial Symmetry ◽  
Electron Density Distribution ◽  
Electron Distribution ◽  
Atoms In Molecules ◽  
Chlorine Atoms ◽  
Asymmetry Parameters ◽  
Cl Atoms

Abstract The 35Cl NQR frequencies and EFG asymmetry parameters at the 35Cl nuclei have been mea­sured for compounds of the series 4-XC6H4MCCl2C(O)C6H5 (M = S and Se, X = H and CH3) at 77 K. The electron distribution at the Cl atoms in all the compounds studied differs from axial symmetry, and is unequal for the two Cl atoms of the CCl2 group. The results of the measurements imply pσ-electron density nonequivalence of Cl atoms in the CCl2 group of these molecules.

A 15N and 13C N.M.R. study of electron distribution in Di- and Tri-azapentadienium salts

1978 ◽  
Vol 31 (5) ◽  
pp. 1005 ◽  
Author(s):  
AJ Jones ◽  
H McNab ◽  
P Hanisch
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Electron Distribution ◽  
Chemical Shifts ◽  
Phenyl Group ◽  
Natural Abundance ◽  
Fourier Methods ◽  
13C Chemical Shifts ◽  
Electron Withdrawal

The 15N and 13C chemical shifts of eight vinamidinium and azavinamidinium cations have been determined at the natural-abundance level by means of Fourier methods. Both 15N and 13C chemical shifts reflect the electron- density distribution in the pentadienium chain, especially in the aryl derivatives in which conjugative stabilization through electron withdrawal by the substituent phenyl group is exhibited.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

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