High resolution electron density mapping for LiF and NaF by maximum entropy method (MEM)

2003 ◽  
Vol 64 (1) ◽  
pp. 43-49 ◽  
Author(s):  
S. Israel ◽  
R. Saravanan ◽  
N. Srinivasan ◽  
R.K. Rajaram
Keyword(s):  
High Resolution ◽  
Maximum Entropy ◽  
Electron Density ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Density Mapping ◽  
Resolution Electron

Electron Density Distribution Obtained from X-Ray Powder Data by the Maximum Entropy Method

1991 ◽  
Vol 35 (A) ◽  
pp. 77-83 ◽  
Author(s):  
Makoto Sakata ◽  
Masaki Takata ◽  
Yoshiki Kubota ◽  
Tatsuya Uno ◽  
Shintaro Kuhazawa ◽  
...  
Keyword(s):  
Density Distribution ◽  
Maximum Entropy ◽  
Electron Density ◽  
Diffraction Data ◽  
Electron Density Distribution ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Nuclear Density ◽  
X Ray ◽  
Distribution Maps

AbstractThe electron density distribution maps for CaF2 and TiO2 (rutile) were obtained from profile fitting of powder diffraction data by a Maximum Entropy Method (MEM) analysis. The resultant electron density maps show clearly the nature of the chemical bonding. In order to interpret the results, the nuclear density distribution was also obtained for rutile from powder neutron diffraction data. In the electron density map for rutile obtained by HEM analysis from the X-ray data, both apical and equatorial bonding can be seen. On the other hand, the nuclear density of rutile Is very simple and shows the thermal vibration of nuclei.

scholarly journals High resolution infrared maps of IRAS galaxies

1991 ◽  
Vol 147 ◽  
pp. 411-412
Author(s):  
S. K. Ghosh ◽  
T. N. Rengarajan ◽  
R. P. Verma
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
The Cross

IRAS has provided infrared maps of a large number of galaxies. However the size of IRAS survey detectors is quite large (∼5′ in the cross-scan direction) and there is a need for improving the resolution of these maps. In order to understand the spatial structure of galaxies, we have generated high resolution maps of 18 large galaxies by deconvolving the IRAS pointed observations from survey detectors as well as from Chopped Photometric Channel (CPC) using Maximum Entropy Method (MEM).

Electron density distribution in the pyroborateMn2B2O5studied by the maximum-entropy method

2005 ◽  
Vol 71 (22) ◽  
Author(s):  
F. S. Sarrat ◽  
R. B. Guimarães ◽  
M. A. Continentino ◽  
J. C. Fernandes ◽  
A. C. Doriguetto ◽  
...  
Keyword(s):  
Density Distribution ◽  
Maximum Entropy ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Maximum Entropy Method ◽  
Entropy Method

Observation of orientational disorder in the hexagonal stuffed tridymite Sr0.864Eu0.136Al2O4by the maximum-entropy method

2004 ◽  
Vol 37 (5) ◽  
pp. 698-702 ◽  
Author(s):  
H. Yamada ◽  
W. S. Shi ◽  
C. N. Xu
Keyword(s):  
Maximum Entropy ◽  
Electron Density ◽  
Maximum Entropy Method ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
Atomic Displacement ◽  
Entropy Method ◽  
Apical Oxygen ◽  
Threefold Axis ◽  
Density Image

The crystal structure of a strontium europium aluminate, Sr0.864Eu0.136Al2O4, with a novel hexagonal form was investigated by a combination of Rietveld analysis and the maximum-entropy method (MEM) with synchrotron X-ray powder diffraction data. The electron density image calculated by the MEM/Rietveld method revealed that the apical oxygen ion in the AlO4tetrahedron has a broad distribution corresponding to an extraordinarily large atomic displacement parameter. This structure could be expressed by a split-atom model, with which the Rietveld refinement gaveRwp= 2.99% andRB= 4.16%. Subsequently, MEM-based pattern fitting (MPF) decreased theRfactors toRwp= 2.81% andRB= 2.34% and the electron density image clearly showed that the apical oxygen ions of the AlO4tetrahedra are split over three sites around a threefold axis involving an elongated distribution of the residual O ions along thecaxis. These results suggest that AlO4tetrahedra in Sr0.864Eu0.136Al2O4are orientationally disordered.

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