Electric field gradient efg tensor

Here, I, I, and I are angular momentum operators, Q is the quadrupole moment of the nucleus, the z component, and r the asymmetry parameter of the electric field gradient (efg) tensor. We wish to construct the Hamiltonian for a nucleus if the efg jumps at random between HS and LS states. For this purpose, a random function of time / (f) is introduced which can assume only the two possible values +1. For convenience of presentation we assume equal... 

Solid state 2H NMR parameters are almost exclusively governed by the quadrupole interaction with the electric field gradient (EFG) tensor at the deuteron site.1 8 The EFG is entirely intramolecular in nature. Thus molecular order and mobility are monitored through the orientation of individual C-2H bond directions. Therefore, 2H NMR is a powerful technique for studying local molecular motions. It enables us to discriminate different types of motions and their correlation times over a wide frequency range. Dynamics of numerous polymers has been examined by solid state 2H NMR.1 3,7,9 Dynamic information on polypeptides by NMR is however limited,10 26 although the main-chain secondary structures of polypeptides in the solid have been extensively evaluated by 13C and 15N CP/MAS NMR.27,28... 

Hm describes the hyperfine interaction with the 57Fe nucleus. A is the magnetic hyperfine tensor and Hq describes the interaction of the quadrupole moment Q of the 7=3/2 nuclear excited state with the (traceless) electric field gradient (EFG) tensor V (the nuclear ground state has 7= 1/2 and lacks a spectroscopic quadrupole moment). In the absence of magnetic effects (for instance, for S 0, or S = integer for B = 0), the Mossbauer spectrum consists of a doublet with quadrupole splitting ... 

As described above for complexes of HCl with NH3 and PH3, Bacskay et al. have computed the vibrationally averaged component of the electric field gradient (EFG) tensor along... 

While eq N) is the largest principal component of the electric field gradient (EFG) tensor at the site of the quadrupolar nucleus. All the information about the structure of the molecule and interactions is in the eq N) term. In the gas-phase (at low symmetry positions) the EFG is entirely of intermolecular origin. In the condensed phases (liquids and solids), intermolecular interactions may have a substantial influence on the observed EFG. 

The molecular structures and intramolecular hydrogen bonding for salicylic (I), 2-hydroxythiobenzoic (II), 2-hydroxythionobenzoic (III) and 2-hydroxy-dithiobenzoic acids (IV) were studied precisely by ab initio method and density functional theory. The carbonyl electrical field-gradient (EFG) tensor and chemical shift (CS) tensor of a urea-type functional group, R NH-C(0)-NHR were determined. Quantum chemical calculations revealed very large... 

Computing Electric Field Gradient Tensors to Study Cl, and Quadrupolar Spins Recent advances in theory and computing power have made the computation of the electric field gradient (EFG) tensor parameters possible by first-principles methods and made quadrupolar spins a more valuable source of chemical information in solids. This section focuses on recent advances on the computational and experimental studies of APIs exploiting Cl, and quadrupolar nuclei. 

A nucleus with nonzero nuclear quadrupole moment is subject to electric quadrupole interaction if it is experiencing an inhomogeneous electric field. The latter is characterized by the electric field gradient (EFG) tensor defined by = —V°VVj where indicates dyadic product (the matrix product of a column vector and a row vector resulting in a square matrix). The Vij element of the EFG tensor is given by... 

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