نتایج جستجو برای: nmr chemical shielding

تعداد نتایج: 435629  

Abstract The structural and electrostatic properties of the single-walled two representative (8, 0) zigzag and (4, 4) armchair models of pristine and GaAs-doped on boron phosphide nanotubes (BPNTs) was investigated by calculating the nuclear magnetic resonance tensors and with performing the density function theory. The geometrical structures of all representative pristine and GaAs-doped mode...

Journal: :journal of physical & theoretical chemistry 2009
k. shahanipour t. nejad salari f. mollaamin m. monajjemi

we have evaluated the nmr shielding tensors for active site of oxidized ayurin azurin is classified to atype i copper protein with et functionality. we have computed nmr shielding tensor at .133lyp and idlevels by usum 6-3ig basis set in the gas phase and in different solvents such as water, hmso,nitromethane, methanol, ethanol, acetone ,dicholoroethane. these solvents represent a wide range of...

Journal: :journal of physical & theoretical chemistry 2014
m. anafcheh f. naderi m. ezatvar h. masoomi

dft calculations were applied to evaluate the electronic and magnetic properties of zigzag bc2nnanotubes based on the 13c, 15n, and 11b nmr parameters and natural charge analysis. weconsidered three types of zigzag nanotubes, zz-1, zz-2, and zz-3 (n, 0) with n = 8, 12, and 14. theobtained results indicated the divisions of the electrostatic environments around c nuclei into a fewlayers, consist...

Journal: :journal of physical & theoretical chemistry 2005
m. monajemi m.a seyed sajjadi r. sayyadi g. ghassemi

structural and magnetic properties of purine and pyrimidine nucleotides (cmp, ump, dtmp, amp, gmp, imp) were studied at different levels of ab initio molecular orbital theory. these calculations were performed at the hartree-fock level and density functional b3lyp methods. geometries were fully optimized by following cs symmetry restrictions. the standard 6-31g** basis set which includes polari...

2002
Elaine A. Moore

Recent ab initio calculations of cobalt NMR shielding show that DFT-GIAO calculations using hybrid functionals are found to reproduce experimental values well. This method is used to calculate the variation of the cobalt NMR shielding tensor of sqaure pyramidal nitrosyl complexes with respect to the CoNO geometry and to differing basal ligands. The isotropic shielding is shown to have a large n...

2011
Thibault Charpentier

In 2001, Mauri and Pickard introduced the gauge including projected augmented wave (GIPAW) method that enabled for the first time the calculation of all-electron NMR parameters in solids, i.e. accounting for periodic boundary conditions. The GIPAW method roots in the plane wave pseudopotential formalism of the density functional theory (DFT), and avoids the use of the cluster approximation. Thi...

Journal: :Journal of the American Chemical Society 2001
R H Havlin D D Laws H M Bitter L K Sanders H Sun J S Grimley D E Wemmer A Pines E Oldfield

We have carried out a solid-state magic-angle sample-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic investigation of the (13)C(alpha) chemical shielding tensors of alanine, valine, and leucine residues in a series of crystalline peptides of known structure. For alanine and leucine, which are not branched at the beta-carbon, the experimental chemical shift anisotropy (CSA) spans (...

Journal: :Journal of Physical Chemistry Letters 2021

The resolving power of solid-state nuclear magnetic resonance (NMR) crystallography depends heavily on the accuracy computational predictions NMR chemical shieldings candidate structures, which are usually taken to be local minima in potential energy. To test limits this approximation, we systematically study importance finite-temperature and quantum fluctuations for 1H, 13C, 15N polymorphs thr...

Journal: :Machine learning: science and technology 2021

Abstract The requirement for accelerated and quantitatively accurate screening of nuclear magnetic resonance spectra across the small molecules chemical compound space is two-fold: (1) a robust ‘local’ machine learning (ML) strategy capturing effect neighborhood on an atom’s ‘near-sighted’ property—chemical shielding; (2) reference dataset generated with state-of-the-art first-principles method...

G. Ghassemi M. Monajemi M.A Seyed Sajjadi R. Sayyadi

Structural and magnetic properties of purine and pyrimidine nucleotides (CMP, UMP, dTMP, AMP, GMP, IMP) were studied at different levels of ab initio molecular orbital theory. These calculations were performed at the hartree-fock level and density functional B3LYP methods. Geometries were fully optimized by following Cs symmetry restrictions. The standard 6-31G** basis set which includes polari...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید