نتایج جستجو برای: nmr shielding
تعداد نتایج: 67435 فیلتر نتایج به سال:
In this research, we studied the structure, properties and NMR parameters of interaction F2 gas with pristine and 3C-doped (8, 0) zigzag models of boron phosphide nanotubes (BPNTs). in order to reach these aims, we considered four different configurations for adsorption of F2gas on the outer and inner surfaces of BPNTs. The structures of all models were optimized by using density functional the...
Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrize...
In the present work a set of formal relations connecting different approaches to calculate relativistic effects on magnetic molecular properties are proven. The linear response (LR) within the elimination of the small component (ESC), Breit Pauli, and minimal-coupling approaches are compared. To this end, the leading order ESC reduction of operators within the minimal-coupling four-component ap...
A series of molybdate, MoO4(2-), salts have been studied using solid-state 95Mo NMR spectroscopy at applied magnetic field strengths of 11.75, 17.63 and 21.14 T. In contrast to previous investigations, the principal components of the Mo shielding and EFG tensors have been obtained, as well as their relative orientations. At the fields employed, the anisotropic Mo shielding and quadrupolar inter...
We have used solid-state 17O NMR experiments to determine the 17O quadrupole coupling (QC) tensor and chemical shift (CS) tensor for the carbonyl oxygen in p-nitro-[1-(17)O]benzaldehyde. Analyses of solid-state 17O NMR spectra obtained at 11.75 and 21.15 T under both magic-angle spinning (MAS) and stationary conditions yield the magnitude and relative orientation of these two tensors: CQ = 10.7...
We have used ab initio quantum chemical techniques to compute the (13)C(alpha) and (13)C(beta) shielding surfaces for the 14 amino acids not previously investigated (R. H. Havlin et al., J. Am. Chem. Soc. 1997, 119, 11951-11958) in their most popular conformations. The spans (Omega = sigma(33) - sigma(11)) of all the tensors reported here are large ( approximately 34 ppm) and there are only ver...
Complete nuclear magnetic resonance (NMR) chemical-shielding tensors, sigma, have been computed at different levels of density-functional theory (DFT), within the gauge-including atomic orbital (GIAO) formalism, for the atoms of the peptide model For-L-Ala-NH2 as a function of the backbone dihedral angles phi and psi by employing a dense grid of 10 degrees. A complete set of rigorously orthogon...
The nuclear magnetic shielding tensor is a sensitive probe of the local electronic environment, providing information about molecular structure and intermolecular interactions. The magnetic shielding tensor of the water proton has been determined in hexagonal ice, but in liquid water, where the tensor is isotropically averaged by rapid molecular tumbling, only the trace of the tensor has been m...
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