Ammonia adsorption on the C30B15N15 heterofullerene: DFT study of nuclear magnetic shielding and electric field gradient tensors of N and B nuclei

2011 ◽  
Vol 406 (8) ◽  
pp. 1592-1597 ◽  
Author(s):  
Ehsan Zahedi
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Dft Study ◽  
Magnetic Shielding ◽  
Ammonia Adsorption ◽  
Nuclear Magnetic

EFGShield — A program for parsing and summarizing the results of electric field gradient and nuclear magnetic shielding tensor calculations

2007 ◽  
Vol 85 (7-8) ◽  
pp. 496-505 ◽  
Author(s):  
Samyuktha Adiga ◽  
Dominic Aebi ◽  
David L Bryce
Keyword(s):  
Electric Field ◽  
Computer Program ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Quantum Chemical ◽  
Magnetic Shielding ◽  
Euler Angles ◽  
Chloride Dihydrate ◽  
Shielding Tensor ◽  
Nuclear Magnetic

A computer program (EFGShield) is described that simplifies and summarizes the output from electric field gradient (EFG) and nuclear magnetic shielding tensor calculations performed independently using existing quantum chemical software. In addition to summarizing tensor magnitudes according to conventions commonly used by solid-state NMR spectroscopists, the program provides Euler angles relating the orientations of the EFG and shielding tensor principal axis systems (PAS). An atomic coordinate file is generated that also contains dummy atoms representing the orientations of the EFG and shielding tensor PASs in the molecular framework. We demonstrate the functionality of the program using calculations of the chlorine EFG and shielding tensors for strontium chloride dihydrate and calcium chloride dihydrate. Several models of the chloride environment in these compounds are tested, including those where point charges are used to represent the extended three-dimensional lattices within the self-consistent charge field perturbation approach. The results highlight both the shortcomings and successes of traditional localized orbital-based basis sets in the description of the NMR properties of extended systems. We anticipate that EFGShield will be a useful tool for spectroscopists using quantum chemical software to aid in the interpretation of experimental data.Key words: quantum chemical calculations, computer program, electric field gradient tensor, quadrupolar coupling constant, nuclear magnetic shielding tensor, Euler angles, alkaline earth chloride hydrates.

Electric-field Dependence of Nuclear Magnetic Shielding and Susceptibility of Hydrogen and Hydrogen Fluoride Molecules

1979 ◽  
Vol 34 (11) ◽  
pp. 1279-1282 ◽  
Author(s):  
M. Žaucer ◽  
A. Ažman
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Field Dependence ◽  
Hydrogen Fluoride ◽  
Environmental Effects ◽  
Magnetic Shielding ◽  
Gauge Invariant ◽  
Electric Field Dependence ◽  
Nuclear Magnetic

The components of t h e tensors σ(1), σ(2) and χ(1), χ(2) which describe the linear and quadratic electric-field dependences of the nuclear magnetic shielding and susceptibility are computed for H2 and HF molecules using a gauge invariant double finite perturbation SCF approach. This approach is suitable for the discussion of intramolecular and intermolecular environmental effects and the effect of electric-field gradient is pointed out

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 Dynamics of Solid Proteins by Means of Nuclear Magnetic Resonance Relaxometry

Biomolecules ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 652 ◽  
Author(s):  
Danuta Kruk ◽  
Elzbieta Masiewicz ◽  
Anna M. Borkowska ◽  
Pawel Rochowski ◽  
Pascal H. Fries ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Protein Dynamics ◽  
Spin Lattice Relaxation ◽  
Closed Form Expression ◽  
Quadrupole Relaxation ◽  
Nuclear Magnetic

1H Nuclear magnetic resonance (NMR) relaxometry was exploited to investigate the dynamics of solid proteins. The relaxation experiments were performed at 37 °C over a broad frequency range, from approximately 10 kHz to 40 MHz. Two relaxation contributions to the overall 1H spin–lattice relaxation were revealed; they were associated with 1H–1H and 1H–14N magnetic dipole–dipole interactions, respectively. The 1H–1H relaxation contribution was interpreted in terms of three dynamical processes occurring on timescales of 10−6 s, 10−7 s, and 10−8 s, respectively. The 1H–14N relaxation contribution shows quadrupole relaxation enhancement effects. A thorough analysis of the data was performed revealing similarities in the protein dynamics, despite their different structures. Among several parameters characterizing the protein dynamics and structure (e.g., electric field gradient tensor at the position of 14N nuclei), the orientation of the 1H–14N dipole–dipole axis, with respect to the principal axis system of the electric field gradient, was determined, showing that, for lysozyme, it was considerably different than for the other proteins. Moreover, the validity range of a closed form expression describing the 1H–14N relaxation contribution was determined by a comparison with a general approach based on the stochastic Liouville equation.

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