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Abstract
Solidstate NMR spectra have historically been assigned using simple relationships between NMR parameters, e.g., the isotropic chemical shift, and aspects of the local structure of the material in question, e.g., bond angles or lengths. Density functional theory (DFT) calculations have effectively superseded these relationships in many cases, owing to the accuracy of the NMR parameters typically able to be calculated. However, the computational time required for DFT calculations may still be prohibitive, particularly for very large systems, where structurespectrum relationships must still be used to interpret the NMR spectra. Here we show that, for calcined aluminophosphates (AlPOs), structurespectrum relationships relying on either the mean POAl angle or the mean PO distance, both suggested in previous literature, provide a poor prediction of the ^{31}P isotropic shielding, σ_{iso}, calculated by DFT. However, a relationship dependent on both parameters yields predicted σ_{iso} in excellent agreement with DFT, with a mean error of ~1.6 ppm. The predictive ability of the relationship is not improved by introducing further parameters (many used in previous work) describing the local structure, suggesting that the twoparameter relationship is close to an optimum balance between accuracy and overparameterisation. The ability to predict accurately the outcome of DFTlevel calculations will be of particular interest in cases where the actual calculations would be impractical or even impossible with current computational hardware, or where many such calculations are required quickly.
Original language  English 

Pages (fromto)  2328523296 
Number of pages  12 
Journal  Journal of Physical Chemistry C 
Volume  118 
Issue number  40 
Early online date  15 Sept 2014 
DOIs  
Publication status  Published  2014 
Keywords
 Zeolites
 Solidstate NMR
 Density functional theory
 Local structure
 Spectral prediction
 Empirical relationships
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Dive into the research topics of 'Investigating Relationships between the Crystal Structure and ^{31}P Isotropic Chemical Shifts in Calcined Aluminophosphates'. Together they form a unique fingerprint.Projects
 3 Finished

EPSRC Strategic partner projects applica: An active, provenancepreserving scientific data store
Dearle, A. (PI), Dobson, S. A. (CoI), Henderson, T. (CoI), Philp, D. (CoI) & Woollins, J. D. (CoI)
1/08/11 → 30/06/12
Project: Standard

EPSRC Strategic partner projectsapplica: Expanding the capability for variable temperature solidstate NMR in St Andrews
Ashbrook, S. E. (PI)
1/08/11 → 30/06/12
Project: Standard

HighResolution SolidState NMR: HighResolution SolidState NMR in St Andrews: Development and Applications
Ashbrook, S. E. (PI), Morris, R. E. (CoI), Wormald, P. (CoI) & Wright, P. A. (CoI)
1/08/07 → 13/01/11
Project: Standard