Electric field gradient tensors nuclear quadrupole coupling constant

X the 33S nuclear quadrupole coupling constant (expressed in frequency units), and r] the asymmetry parameter of the electric field gradient tensor (0[Pg.21]

For nuclei with /> 1, the quadrupole coupling constant is defined as the product of the nuclear quadruple moment eQ and the maximum principle value of electric field gradient tensor q. 

Nuclear Quadrupole Coupling constants measure the,electric field gradient tensor at a nucleus in a molecule. The field gradients in free molecules are determined by the electronic structure, but, in the solid state, are affected by environmental factorsj hence their application to the study of inclusion complexes. 

The product of the nuclear quadrupole moment with the electric-field-gradient tensor divided by ft, i.e. k Rk)/ i is called the nuclear quadrupole coupling tensor, while is called the nuclear quadrupole coupling constant. The lat-... 

B3LYP level with the 6-311+- -G (d,P) standard basis set, have been used to characterize the and electric field gradient (EFG) in various bisphosphonate derivatives. The calculated EFG tensors were used to determine the and nuclear quadrupole coupling constant (y) and asymmetry parameter (/ ). For a better understanding of the bonding and electronic structure of bisphosphonates, the isotropic and anisotropic NMR chemical shieldings were calculated for the and P nuclei... 

Classically, the electric field gradient at a nucleus is produced by the arrangement of charges (i.e., other nuclei and electrons) about that nucleus 66). If the nucleus is quad-rupolar, as in the case of 27A1, then the interaction of its nuclear quadrupole moment, eQ, with the largest component of the EFG tensor, V33, is defined as the quadrupolar coupling constant, CQ ... 

For Zn SSNMR spectroscopy, the observed spectrum is usually dominated by the nuclear electric quadrupolar interaction unless the zinc sits at a site with spherical symmetry (such as tetrahedral, octahedral and cubic sites). This anisotropic interaction originates from the coupfing between the quadrupole moment (eQ) of the nucleus and the electric field gradient (EFG) at the nuclear site. The EFG is described by a second-rank tensor that can be diagonalized in a principal axis system (PAS). In the PAS, the EFG is described by three components, which are ordered in such that I Fxx I kVy I ud they satisfy FxxT TyyT Tzz fi-The quadrupolar interaction is characterized by two parameters one is quadrupolar coupling constant ... 

As outlined in section 1.3.2., the nuclear quadrupole interaction is characterized by two parameters, the coupling constant eQVz expressed in suitable energy units, and an asymmetry parameter tj indicating the degree of departure of the electric field gradient (efg) tensor Fy from axial symmetry. Information relevant to the lanthanide-containing metal, alloys, or compound is contained in these two parameters, since from the standpoint of the physics or chemistry of solids the quadrupole moment Q is taken to be a known property of the nuclear state. 

Despite the importance of the nuclear quadrupole coupling in affecting the rotational spectra, the literature concerning the theoretical predictions of its related constants is rather limited. A significant example is provided by the recent investigation performed on the hyperfine structure in the rotational spectra of bromofluoromethane [75]. The experimental determination was supported by quantum chemical calculations of the nuclear quadrupole-coupling and spin-rotation tensors of Br and Br, performed at the CCSD(T) level in conjunction with core-valence correlation-consistent bases. Zero-point vibrational (ZPV) corrections were computed at the MP2 level in conjunction with the cc-pCVTZ basis set, whereas relativistic effects on the electric field gradient at the bromine... 

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