NQR parameters: Electric field gradient tensor and asymmetry parameter studied in terms of density functional theory

2002 ◽  
Vol 91 (3) ◽  
pp. 284-296 ◽  
Author(s):  
J. N. Latosi?ska
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Asymmetry Parameter ◽  
Density Functional ◽  
Electric Field Gradient Tensor ◽  
Gradient Tensor ◽  
Functional Theory ◽  
Nqr Parameters

DENSITY FUNCTIONAL THEORY STUDY OF BINDING ENERGIES, 7Li NUCLEAR MAGNETIC SHIELDING, AND ELECTRIC FIELD GRADIENT TENSORS ON THE SMALL CLUSTERS OF LinHm (m ≤ n ≤ 4)

2007 ◽  
Vol 06 (04) ◽  
pp. 959-973 ◽  
Author(s):  
MEHDI D. ESRAFILI ◽  
FATEMEH ELMI ◽  
NASSER L. HADIPOUR
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Density Functional ◽  
Three Dimensional ◽  
Lithium Hydride ◽  
Binding Energies ◽  
Magnetic Shielding ◽  
Functional Theory

The binding energies, geometries, 7 Li magnetic shielding, and electric field gradient tensors of hydrogenated lithium clusters, Li n H m (m ≤ n ≤ 4), were studied via density functional theory approach. We optimized the structures using B3LYP functional and 6-311++G (2d,2p) basis set. The calculated binding energies of lithium hydride clusters indicate that hydrogenation energy of Li n H m clusters decreases as the number of hydrogen atoms within the cluster increases. Our calculations also showed that for n = 4 clusters, the three-dimensional structure is more stable than the planar one. The study of the trends in the 7 Li magnetic shielding isotropy, σiso, and anisotropies, Δσ, values are explained in terms of the interplay between the electronic and geometrical effects. The variations in the 7 Li nuclear quadrupole coupling constants, χ, and their associated asymmetry parameters, ηQ, for different isomers of the lithium hydride clusters and the influence of hydrogenation on the EFG tensors are also discussed. For n = 4, we obtained a noticeable difference in the χ value from the planar to the three-dimensional structures. The atoms in molecules (AIM) analysis at the Li–H bond critical point reveals remarkably different topographical properties of the charge density and associated Laplacian fields for the planar and three-dimensional lithium hydride clusters.

scholarly journals Магнитные состояния ионов Fe-=SUP=-2+-=/SUP=- в Fe-=SUB=-x-=/SUB=-Mn-=SUB=-1-x-=/SUB=-S, индуцированные химическим давлением

2021 ◽  
Vol 63 (1) ◽  
pp. 69
Author(s):  
Г.М. Абрамова ◽  
Ю.В. Князев ◽  
О.А. Баюков ◽  
С.П. Кубрин
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Spin State ◽  
Asymmetry Parameter ◽  
Principal Axis ◽  
High Spin State ◽  
Electric Field Gradient Tensor ◽  
Gradient Tensor ◽  
Chemical Pressure

The effect of chemical pressure (x) on the spin state of iron ions in FexMn1-xS single crystals (0.12≤ x≤0.29) is studied by the method of Mössbauer spectroscopy in the range 4.2-300 K. Features of the formation of the paramagnetic and antiferromagnetic phases for solid solutions are revealed. It was found that when x changes in FexMn1-xS, the Mn2 + cations are replaced by Fe2 + cations in the high-spin state. A decrease in the interionic distances in FexMn1-xS causes a change in the state of Fe2 + ions in the samples at x = 0.25 and 0.29. In the magnetically ordered phase at 4.2 K, the changes in the asymmetry parameter of the electric field gradient tensor (EFG) and the angle between the directions of the magnetic moment and the principal axis of the electric field gradient from 21o in the sample from x = 0.12 to 33o at x = 0.29 were observed.

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