First-Principles Calculations of the E′1 Center in Quartz: Structural Models, 29Si Hyperfine Parameters and Association with Al Impurity

2012 ◽  
pp. 161-175 ◽  
Author(s):  
Zucheng Li ◽  
Yuanming Pan
Keyword(s):  
First Principles ◽  
Structural Models ◽  
First Principles Calculations ◽  
Hyperfine Parameters

Properties of Iron Atoms at Grain Boundaries in Fe and Fe72Al28

1998 ◽  
Vol 527 ◽  
Author(s):  
O. Schneeweiss ◽  
I. Turek ◽  
J. Čermák ◽  
P. Lejček
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
First Principles ◽  
Magnetic Moments ◽  
Emission Mössbauer Spectroscopy ◽  
First Principles Calculations ◽  
Hyperfine Parameters ◽  
Impurity Atoms ◽  
Atomic Spacing

ABSTRACTLocation of diffused 57Co atoms in single crystals, bicrystals and polycrystals of pure iron and Fe72Al28alloy were investigated by means of emission Mössbauer spectroscopy. To interpret the results, first principles calculations of iron atom magnetic moments and hyper-fine field were carried out. From comparison of M6ssbauer spectra of single crystals with those of bicrystals and polycrystals, an information about grain boundary positions occupied by diffusing atoms is obtained. It is shown that about 5% of the diffusing atoms at the {112} grain boundary of iron are located at the positions either having impurity atoms in the nearest neighbourhood or characterized by larger atomic spacing in comparison with the bulk. In the Fe72Al28 a dominating portion of diffusing atoms have different surrounding than in grain volume. An enrichment of grain boundaries by aluminum could explain their hyperfine parameters.

First-principles calculations of hyperfine parameters

1993 ◽  
Vol 47 (8) ◽  
pp. 4244-4255 ◽  
Author(s):  
Chris G. Van de Walle ◽  
P. E. Blöchl
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Hyperfine Parameters

THE ${\rm{Si}} (111)\mbox{-}(\sqrt{3} \times \sqrt{3})$R30°-Ag AND -Au SURFACE STRUCTURES FROM FIRST PRINCIPLES CALCULATIONS

1993 ◽  
Vol 07 (12) ◽  
pp. 787-795
Author(s):  
Y.G. DING ◽  
C.T. CHAN ◽  
K.M. HO
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Theoretical Calculations ◽  
Structural Models ◽  
Small Variation ◽  
Surface Structures ◽  
First Principles Calculations ◽  
Structural Details ◽  
Electronic And Structural Properties ◽  
Stm Images

The electronic and structural properties of the [Formula: see text]R30°- Ag and Au surfaces are investigated using first-principles total energy calculations. The structures of Au and Ag are in fact quite similar and belong to the same class of structural models. However, small variation in the structural details can give rise to quite different observed STM images, as revealed in the theoretical calculations.

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