Solid-state NMR calculations for metal oxides and gallates: Shielding and quadrupolar parameters for perovskites and related phases

Middlemiss, Derek S.; Blanc, Frédéric; Pickard, Chris J.; Grey, Clare P.

doi:10.1016/j.jmr.2010.01.004

Cited by 43 publications

(52 citation statements)

References 69 publications

(114 reference statements)

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“…It is noted that one of the sources of error is that the calculations rely on the motionally and spatially averaged structure determined by diffraction and not the local structure experienced on the NMR timescale. Approaches to incorporate such effects in calculations beyond pure DFT are challenging, but are a possible interesting future direction [50].…”

Section: First Principles Calculations Of Nmr Parametersmentioning

confidence: 99%

“…Hence the significantly higher broadening requires either some of the wideline techniques or make use of the much faster spinning and higher magnetic fields available. 71 Ga NMR is now being increasingly used to distinguish GaO 4 and GaO 6 on the basis of their differing chemical shifts [44,50]. The ability to distinguish and quantify these sites in materials is at approximately the same state of development as 27 Al was 15 years ago.…”

Section: Half-integer Spin High-quadrupolar Nucleimentioning

confidence: 99%

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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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Section: First Principles Calculations Of Nmr Parametersmentioning

confidence: 99%

Section: Half-integer Spin High-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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“…The problems manifest mainly in the common observation that within a series of compounds the computed shielding parameters for a particular nucleus show systematic error when compared to the measured values. 13,[15][16][17][18][19][20] For example in the case of fluorides or oxides the shielding parameters computed within DFT using the standard PBE 21 exchange correlation functional are correlate well with the measured values, but the slope of the line representing the relation between the experimental and theoretical data is close to 0.8 instead of 1.0. 15,16 This intriguing and very systematic error has its origin in the deficiencies of the approximate density functional.…”

Section: Introductionmentioning

confidence: 97%

“…13,[15][16][17][18][19][20] For example in the case of fluorides or oxides the shielding parameters computed within DFT using the standard PBE 21 exchange correlation functional are correlate well with the measured values, but the slope of the line representing the relation between the experimental and theoretical data is close to 0.8 instead of 1.0. 15,16 This intriguing and very systematic error has its origin in the deficiencies of the approximate density functional. For instance it has been shown before that for the 17 O chemical shift the error in CaO is significantly larger than for many other oxides and that the problem arises due to Ca 3d orbitals being too close to the valence band maximum, 13 which affects the Ca-3d O-2p hybridization.…”

Section: Introductionmentioning

confidence: 97%

Assessment of DFT functionals with NMR chemical shifts

2013

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Density-functional theory (DFT) calculations of the magnetic shielding for nuclear magnetic resonance (NMR) in solids provide an important contribution for understanding the experimentally observed chemical shifts. It is known that the calculated NMR shielding parameters for a particular nucleus in a series of compounds correlate well with the experimentally measured chemical shifts; however, the slope of a linear fit often differs from the ideal value of 1.0. Focusing on a series of ionic compounds (fluorides, oxides, bromides, and chlorides), we show that the error is caused by the generalized gradient approximation (GGA) to the exchange-correlation functional and it is related to the well-known band-gap problem. In order to devise an ab initio approach that would correctly reproduce the variation of the shifts within a series of compounds, we test various DFT based approaches. A simple GGA + U scheme with the orbital field acting on the cation d states does not work in a general way. Also, the popular hybrid functionals (including the screened versions), which contain some fixed amount of exact exchange, lead to a large overestimation of the necessary slope correction. Surprisingly, the best solution to this problem is offered by a semilocal potential designed by Becke and Johnson to reproduce the optimized exact exchange potential in free atoms. Density functional theory (DFT) calculations of the magnetic shielding for nuclear magnetic resonance (NMR) in solids provide an important contribution for understanding the experimentally observed chemical shifts. It is known that the calculated NMR shielding parameters for a particular nucleus in a series of compounds correlate well with the experimentally measured chemical shifts, however, the slope of a linear fit often differs from the ideal value of 1.0. Focusing on a series of ionic compounds (fluorides, oxides, bromides and chlorides), we show that the error is caused by the generalized gradient approximation (GGA) to the exchange correlation functional and it is related to the well known band-gap problem. In order to devise an ab-initio approach that would correctly reproduce the variation of the shifts within a series of compounds, we test various DFT based approaches. A simple GGA+U scheme with the orbital field acting on the cation d-states does not work in a general way. Also the popular hybrid functionals (like HSE or YS-PBE0), which contain some fixed amount of exact exchange, leads to a large overestimation of the necessary slope correction. Surprisingly, the best solution to this problem is offered by a semi-local potential designed by Becke and Johnson to reproduce the optimized exact exchange potential in free atoms.

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“…In general, it was found that the theoretical results closely track the experimental trends, though some deviations were identified and discussed, particularly in regard to quadrupolar Z Q -values. 202 Muon spin relaxation and 69,71 Ga nuclear quadrupolar resonance local-probe investigations of the kagome compound Pr 3 Ga 5 SiO 14 was shown. Small quasistatic random internal fields develop below 40 K and persist down to the base temperature.…”

Section: Barium ( 137 Ba) (I = 3/2) the Local Ba Environment In B-bamentioning

confidence: 91%

Applications of nuclear shielding

Kuroki¹,

Matsukawa²,

Yasunaga³

2011

Nuclear Magnetic Resonance

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Solid-state NMR calculations for metal oxides and gallates: Shielding and quadrupolar parameters for perovskites and related phases

Cited by 43 publications

References 69 publications

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

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

Assessment of DFT functionals with NMR chemical shifts

Applications of nuclear shielding

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