Bonding and valence electron distributions in molecules. Experimental determination of aspherical electron charge density in tetracyanoethylene oxide

1971 ◽  
Vol 93 (23) ◽  
pp. 5954-5959 ◽  
Author(s):  
D. A. Matthews ◽  
G. D. Stucky
Keyword(s):  
Charge Density ◽  
Experimental Determination ◽  
Valence Electron ◽  
Electron Charge ◽  
Electron Charge Density ◽  
Electron Distributions

Environment Sensitive Embedding Energies of Impurities, and Grain Boundary Relaxation in Iron

1991 ◽  
Vol 238 ◽  
Author(s):  
Genrich L. Krasko
Keyword(s):  
Charge Density ◽  
First Principles ◽  
Electron Charge ◽  
Deformation Wave ◽  
Electron Charge Density ◽  
Impurity Site ◽  
Embedded Atom ◽  
Bcc Iron ◽  
Boundary Relaxation ◽  
Low Solubility

ABSTRACTImpurities, such as H, P, S, B, etc, have a very low solubility in iron, and therefore prefer to segregate at the grain boundaries (GBs). In order to analyze the energetics of the impurities on the iron GB, the LMTO calculations were performed on a simple 8-atom supercel 1 emulating a typical (capped trigonal prism) GB environment. The so-called “environment-sensitive embedding energies” were calculated for H, B, C, N, O, Al, Si, P, and S, as a function of the electron charge density due to the host atoms at the impurity site. It was shown that, at the electron charge density typical of a GB, B and C have the lowest energy among the analyzed impurities, and thus would compete with them for the site on the GB, tending to push the other impurities off the GB. The above energies were then used in a modified Finnis-Sinclair embedded atom approach for calculating the equilibrium interplanar distances in the vicinity of a (111) σ3 tilt GB plane, both for the clean GB and that with an impurity. These distances were found to be oscillating, returning to the equilibrium spacing between (111) planes in bulk BCC iron by the 10th-12th plane off the GB plane. H, B, C, N and O actually dampen the deformation wave (making the oscillation amplitudes less than in the clean GB), while, Al, Si, P and S result in an increase of the oscillations. The effect of B, C, N and O may be interpreted as cohesion enhancement; this conclusion supports our earlier first-principles results [1] on B and C.

X-Ray Electron Charge Density Distribution in Silicon

1986 ◽  
Vol 137 (2) ◽  
pp. 441-447 ◽  
Author(s):  
U. Pietsch ◽  
V. G. Tsirelson ◽  
R. P. Ozerov
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Electron Charge ◽  
Charge Density Distribution ◽  
Electron Charge Density ◽  
X Ray
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