Electric Field Gradient Calculations of Various Borides

1996 ◽  
Vol 51 (5-6) ◽  
pp. 527-533 ◽  
Author(s):  
K. Schwarz ◽  
H. Ripplinger ◽  
P. Blaha
Keyword(s):  
Electric Field ◽  
First Principles ◽  
Density Functional ◽  
The Self ◽  
Full Potential ◽  
Electric Field Gradients ◽  
Charge Density Distribution ◽  
Functional Theory ◽  
Field Gradients ◽  
Self Consistent

Abstract A first-principles method for the computation of electric field gradients (EFG) is illustrated for various borides. It is based on energy band calculations using the full-potential linearized aug-mented plane wave (LAPW) method within density functional theory. From the self-consistent charge density distribution the EFG is obtained without further approximations by numerically solving Poisson's equation. The dependence of the EFG on structure, chemical composition or substitution is demonstrated for the diborides MB2 (with M = Ti, V, Cr, Zr, Nb, Mo, and Ta), the hexaborides (CaB6, SrB6 and BaB6) and boron carbide which is closely related to α-boron.

Electric Field Gradient in Aluminium due to Vacancy and Muon

1992 ◽  
Vol 47 (1-2) ◽  
pp. 45-48
Author(s):  
M. J. Ponnambalam
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Density Functional ◽  
Near Neighbour ◽  
Electric Field Gradients ◽  
Functional Theory ◽  
Field Gradients ◽  
Analytic Expression ◽  
Valence Effect ◽  
Good Agreement

AbstractThe electric field gradients (EFG) in aluminium due to a monovacancy and the interstitial muon are evaluated. The valence effect EFG qv is calculated using perturbed electron density δn(r)values obtained from density functional theory in an analytic expression which is valid at all distances from the impurity. The size effect EFG qs is evaluated using a new oscillatory form for the near neighbour (nn) displacements. The numerical values of qs are computed using fractional nn displacements available in the literature. For the total EFG good agreement with experiment is obtained without the use of any parameter.

scholarly journals 11B and 23Na solid-state NMR and density functional theory studies of electric field gradients at boron sites in ulexite

CrystEngComm ◽  
2013 ◽  
Vol 15 (43) ◽  
pp. 8739 ◽  
Author(s):  
Bing Zhou ◽  
Vladimir K. Michaelis ◽  
Scott Kroeker ◽  
John E. C. Wren ◽  
Yefeng Yao ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Electric Field ◽  
Solid State Nmr ◽  
Density Functional ◽  
Electric Field Gradients ◽  
Functional Theory ◽  
Field Gradients

scholarly journals Screening in Graphene: Response to External Static Electric Field and an Image-Potential Problem

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1561
Author(s):  
Vyacheslav M. Silkin ◽  
Eugene Kogan ◽  
Godfrey Gumbs
Keyword(s):  
Electric Field ◽  
First Principles ◽  
Density Functional ◽  
Potential Problem ◽  
Graphene Monolayer ◽  
Theory Approach ◽  
Static Electric Field ◽  
Charge Density Distribution ◽  
Free Standing ◽  
Functional Theory

We present a detailed first-principles investigation of the response of a free-standing graphene sheet to an external perpendicular static electric field E. The charge density distribution in the vicinity of the graphene monolayer that is caused by E was determined using the pseudopotential density-functional theory approach. Different geometries were considered. The centroid of this extra density induced by an external electric field was determined as zim = 1.048 Å at vanishing E, and its dependence on E has been obtained. The thus determined zim was employed to construct the hybrid one-electron potential which generates a new set of energies for the image-potential states.

Electric Field Gradients Around Point Defects in Metals

1996 ◽  
Vol 51 (5-6) ◽  
pp. 489-505
Author(s):  
Alfred Seeger ◽  
Jörg Ehmann ◽  
Manfred Fähnle
Keyword(s):  
Electric Field ◽  
Ab Initio ◽  
Density Functional ◽  
Local Density ◽  
Energy Levels ◽  
Full Potential ◽  
Good Resolution ◽  
Quadrupole Moments ◽  
Electric Field Gradients ◽  
Field Gradients

The splittings of nuclear energy levels caused by the electric field gradients acting on the quadrupole moments of nuclei in the neighbourhood of atomic defects in cubic metals may serve as ‘‘fingerprints’’ providing us with a unique characterization of these defects. In favourable cases the NQDOR technique (n̲uclear q̲uadrupole d̲ouble r̲esonance) permits sensitive measurements of these splittings with good resolution. The present paper outlines the status of the ab-initio calculation of electric field gradients with emphasis on the theoretical basis (density functional theory with local density approximation) and on the techniques required for handling the specific problems associated with defects. Recent work by the supercell approach on atomic defects in Al and Cu, making use either of the full-potential linearized augmented-plane-wave method or of the ab-initio pseudopotential method, are reported and compared with experiments. The excellent agreement between experiment and theory for the field gradients acting on the nearest-neighbour nuclei of monovacancies in Al demonstrates the reliability and the potential of the theory.

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