The Use of Neutron Diffraction in Charge Density Analysis

1991 ◽  
pp. 225-240 ◽  
Author(s):  
Hartmut Fuess
Keyword(s):  
Neutron Diffraction ◽  
Charge Density ◽  
Density Analysis

scholarly journals Anisotropic displacement parameters for H atoms using an ONIOM approach

2006 ◽  
Vol 62 (5) ◽  
pp. 875-888 ◽  
Author(s):  
Andrew E. Whitten ◽  
Mark A. Spackman
Keyword(s):  
Neutron Diffraction ◽  
Charge Density ◽  
Ab Initio ◽  
Diffraction Data ◽  
Heavy Atom ◽  
Molecular Crystals ◽  
X Ray ◽  
Density Analysis ◽  
Anisotropic Displacement Parameters ◽  
Oniom Approach

X-ray diffraction data cannot provide anisotropic displacement parameters (ADPs) for H atoms, a major outstanding problem in charge-density analysis of molecular crystals. Although neutron diffraction experiments are the preferred source of this information, for a variety of reasons they are possible only for a minority of materials of interest. To date, approximate procedures combine rigid-body analysis of the molecular heavy-atom skeleton, based on ADPs derived from the X-ray data, with estimates of internal motion provided by spectroscopic data, analyses of neutron diffraction data on related compounds, or ab initio calculations on isolated molecules. Building on these efforts, an improved methodology is presented, incorporating information on internal vibrational motion from ab initio cluster calculations using the ONIOM approach implemented in GAUSSIAN03. The method is tested by comparing model H-atom ADPs with reference values, largely from neutron diffraction experiments, for a variety of molecular crystals: benzene, 1-methyluracil, α-glycine, xylitol and 2-methyl-4-nitroaniline. The results are impressive and, as the method is based on widely available software, and is in principle widely applicable, it offers considerable promise in future charge-density studies of molecular crystals.

ChemInform Abstract: Crystal Structure and Charge Density Analysis of Ca(BH4)2.

ChemInform ◽  
2010 ◽  
Vol 41 (13) ◽  
Author(s):  
T. Noritake ◽  
M. Aoki ◽  
M. Matsumoto ◽  
K. Miwa ◽  
S. Towata ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Charge Density ◽  
Density Analysis

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

Neutron diffraction search for the charge density waves in early rare earth metal deuterides RD3 (R ≡; La, Ce)

1984 ◽  
Vol 101 ◽  
pp. 291-297 ◽  
Author(s):  
R.A. Alikhanov ◽  
V.I. Buzin ◽  
N.I. Kulikov ◽  
M.E. Kost ◽  
W. Sikora ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Charge Density ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Charge Density Waves ◽  
Density Waves

scholarly journals Halogen bonding from charge-density analysis

2011 ◽  
Vol 67 (a1) ◽  
pp. C99-C100 ◽  
Author(s):  
E. Espinosa ◽  
T. T. T. Bui ◽  
S. Dahaoui ◽  
E. Aubert ◽  
C. Lecomte ◽  
...  
Keyword(s):  
Charge Density ◽  
Halogen Bonding ◽  
Density Analysis

Ab initio charge density analysis of (B6C)2– and B4C3 species — How to describe the bonding pattern?

2006 ◽  
Vol 84 (5) ◽  
pp. 771-781 ◽  
Author(s):  
Cina Foroutan-Nejad ◽  
Gholam Hossein Shafiee ◽  
Abdolreza Sadjadi ◽  
Shant Shahbazian
Keyword(s):  
Quantum Theory ◽  
Carbon Atom ◽  
Charge Density ◽  
Ab Initio ◽  
Atoms In Molecules ◽  
Central Carbon Atom ◽  
B3lyp Method ◽  
Central Carbon ◽  
Density Analysis ◽  
Concrete Ring

In this study, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM) developed by Bader and co-workers, has been accomplished (using the B3LYP method) on the CB62– anion and three planar isomers of the C3B4 species, which had been first proposed by Exner and Schleyer as examples of molecules containing hexacoordinate carbon atoms. The analysis uncovers the strong (covalent) interactions of boron atoms as well as the "nondirectional" interaction of central carbon atom with those peripheral atoms. On the other hand, instabilities have been found in the topological networks of (B6C)2– and B4C3(para) species. A detailed investigation of these instabilities demonstrates that the topology of charge density has a floppy nature near the equilibrium geometries of the species under study. Thus, these species seems to be best described as complexes of a relatively concrete ring containing boron or carbon atoms and a central carbon atom that is confined in the plane of the molecule, but with nondirectional interactions with the surrounding atoms.Key words: hypervalency, hexacoordinate carbon, quantum theory of atoms in molecules, charge density analysis, ab initio methods.

Experimental charge-density analysis towards predictive materials science

2021 ◽  
Vol 4 (03) ◽  
pp. 50-71
Author(s):  
Leonardo Dos Santos ◽  
Bernardo L. Rodrigues ◽  
Camila B. Pinto
Keyword(s):  
Physical Properties ◽  
Charge Density ◽  
Materials Science ◽  
New Materials ◽  
Wide Applicability ◽  
Density Analysis ◽  
Properties Of Materials ◽  
A Charge ◽  
Experimental Charge Density

The ongoing increase in the number of experimental charge-density studies can be related to both the technological advancements and the wide applicability of the method. Regarding materials science, the understanding of bonding features and their relation to the physical properties of materials can not only provide means to optimize such properties, but also to predict and design new materials with the desired ones. In this tutorial, we describe the steps for a charge-density analysis, emphasizing the most relevant features and briefly discussing the applications of the method.

scholarly journals Experimental charge density analysis for doxycycline

2015 ◽  
Vol 71 (a1) ◽  
pp. s409-s410
Author(s):  
Anna M. Makal
Keyword(s):  
Charge Density ◽  
Density Analysis ◽  
Experimental Charge Density

scholarly journals Nature of Noncovalent Carbon-Bonding Interactions Derived from Experimental Charge-Density Analysis

ChemPhysChem ◽  
2015 ◽  
Vol 16 (12) ◽  
pp. 2530-2533 ◽  
Author(s):  
Eduardo C. Escudero-Adán ◽  
Antonio Bauzá ◽  
Antonio Frontera ◽  
Pablo Ballester
Keyword(s):  
Charge Density ◽  
Density Analysis ◽  
Experimental Charge Density ◽  
Carbon Bonding
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