All-electron magnetic response with pseudopotentials: NMR chemical shifts

Pickard, Chris J.; Mauri, Francesco

doi:10.1103/physrevb.63.245101

Cited by 1,664 publications

(2,111 citation statements)

References 34 publications

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“…The GIPAW method 58 , used with ultrasoft Vanderbilt-type pseudo-potentials 59,60 , provides an efficient method to calculate chemical shifts in crystalline solids 61 .…”

Section: D Dft Calculationsmentioning

confidence: 99%

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Baias

Widdifield

Dumez

et al. 2013

Phys. Chem. Chem. Phys.

164

251

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A protocol for the ab initio crystal structure determination of powdered solids at natural isotopic abundance by combining solid-state NMR spectroscopy, crystal structure prediction, and DFT chemical shift calculations was evaluated to determine the crystal structures of four small drug molecules: cocaine, flutamide, flufenamic acid, and theophylline. For cocaine, flutamide and flufenamic acid, we find that the assigned 1 H isotropic chemical shifts provide sufficient discrimination to determine the correct structures from a set of predicted structures using the root-mean-square deviation (rmsd) between experimentally determined and calculated chemical shifts. In most cases unassigned shifts could not be used to determine the structures. This method requires no prior knowledge of the crystal structure, and was used to determine the correct crystal structure to within an atomic rmsd of less than 0.12 Å with respect to the known reference structure. For theophylline, the NMR spectra are too simple to allow for unambiguous structure selection.

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“…The GIPAW method 58 , used with ultrasoft Vanderbilt-type pseudo-potentials 59,60 , provides an efficient method to calculate chemical shifts in crystalline solids 61 .…”

Section: D Dft Calculationsmentioning

confidence: 99%

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Baias

Widdifield

Dumez

et al. 2013

Phys. Chem. Chem. Phys.

164

251

View full text Add to dashboard Cite

show abstract

“…Magnetic resonance parameters were calculated using the GIPAW [73][74][75][76] approach which enables the calculation 70 of chemical shifts, electric field gradients and J couplings. Calculations were performed using the experimental X-ray diffraction crystal structure of lithium diborate (ICSD reference code: 65930), as well as geometry optimised (CASTEP) structures (both at X-ray diffraction and optimised 75 lattice parameters).…”

Section: First-principles Calculation Of 2 J Bb Couplingsmentioning

confidence: 99%

Towards homonuclear J solid-state NMR correlation experiments for half-integer quadrupolar nuclei: experimental and simulated 11B MAS spin-echo dephasing and calculated 2JBB coupling constants for lithium diborate

Barrow

Yates

Feller

et al. 2011

Phys. Chem. Chem. Phys.

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is observed: the B3 (larger C Q ) site dephases more slowly than the B4 site at all investigated MAS frequencies (5 to 20 kHz) at 14.1 T. Increasing the MAS frequency leads to markedly slower dephasing for the B3 site, while there is a much less evident effect for the B4 site. Considering samples at 5, 25, 80 (natural abundance) and 100 % 11 B isotopic 15 abundance, dephasing becomes faster for both sites as the 11 B isotopic abundance increases. The experimental behaviour is rationalised using density matrix simulations for two and three dipolarcoupled 11 B nuclei. The experimentally observed slower dephasing for the larger C Q (B3) site is reproduced in all simulations and is explained by the reintroduction of the dipolar coupling by the so-called "spontaneous quadrupolar-driven recoupling mechanism" having a different dependence 20 on the MAS frequency for different quadrupolar frequencies. Specifically, isolated spin-pair simulations show that the spontaneous quadrupolar-driven recoupling mechanism is most efficient when the quadrupolar frequency is equal to twice the MAS frequency. While for isolated spin-pair simulations, increasing the MAS frequency leads to faster dephasing, agreement with experiment is observed for three-spin simulations which additionally include the homogeneous nature of the 25 homonuclear dipolar coupling network. First-principles calculations, using the GIPAW approach, of the 2 J 11B-11B couplings in lithium diborate, metaborate and triborate are presented: a clear trend is revealed whereby the 2 J 11B-11B couplings increase with increasing B-O-B bond angle and B-B distance. However, the calculated 2 J 11B-11B couplings are small (0.95, 1.20 and 2.65 Hz in lithium diborate), thus explaining why no zero crossing due to J modulation is observed experimentally, 30 even for the sample at 25 % 11 B where significant spin-echo intensity remains out to durations of 200 ms.

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“…This creates a smoother approximation to the wavefunction and reduces the number of plane waves required, thereby increasing the computational efficiency. This has been implemented as the CASTEP code [48,49] which can also calculate the shielding as a linear response of the system to B o . A very recent example specifically targeted at using such an approach for materials applications was to calculate the 17 O and 71 Ga NMR interaction parameters from a series of relatively simple oxides and gallates.…”

Section: First Principles Calculations Of Nmr Parametersmentioning

confidence: 99%

“…Nuclei in this group include 25 Mg, 33 S, 35,37 Cl, 43 Ca, 47,49 Ti, 73 Ge, 91 Zr, 95,97 Mo and 135,137 Ba. Examples of developments of all these nuclei can be found in the literature in the last decade, but a few illustrative cases will be given here.…”

Section: Half-integer Spin Low-quadrupolar Nucleimentioning

confidence: 99%

Recent technique developments and applications of solid state NMR in characterising inorganic materials

Hanna

Smith

2010

Solid State Nuclear Magnetic Resonance

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A broad overview is given of some key recent developments in solid state NMR techniques that have driven enhanced applications to inorganic materials science. Reference is made to advances in hardware, pulse sequences and associated computational methods (e.g. first principles calculations, spectral simulation), along with their combination to provide more information about solid phases. The resulting methodology has allowed more nuclei to be observed and more structural information to be extracted. Cross referencing between experimental parameters and their calculation from the structure has seen an added dimension to NMR as a characterisation probe of materials. Emphasis is placed on the progress made in the last decade especially from those nuclei that were little studied previously. The general points about technique development and the increased range of nuclei observed are illustrated through a range of specific exemplars from inorganic materials science.

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All-electron magnetic response with pseudopotentials: NMR chemical shifts

Cited by 1,664 publications

References 34 publications

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Towards homonuclear J solid-state NMR correlation experiments for half-integer quadrupolar nuclei: experimental and simulated 11B MAS spin-echo dephasing and calculated 2JBB coupling constants for lithium diborate

Recent technique developments and applications of solid state NMR in characterising inorganic materials

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