GIPAW method

Figure 2.29 CP MAS NMR spectra of (A) Leu-enkephalin H20 and (B) Leu-enkephalin-2H20-2DMF, recorded at a spinning rate of 12 kHz. The resonances are assigned employing GIPAW method. Reprinted from Ref. [96]. Copyright 2014 American Chemical Society.

Recent years have witnessed the incredible progress in advance of calculation of NMR parameters in the soHd matter. State-of-the-art in this field was recendy exhaustively discussed in review article published hy Bonhomme et al. [170]. In the cited paper, which mostly focuses on latest applications of GIPAW method approach, there is also short section dedicated to study of amino acids and peptides. Thus, in our report we wiU draw attention to those works which were pubhshed last years or employed other techniques than GIPAW. 

First-principles calculations of NMR parameters for solid peptides have a long-standing history. Number of spectacular results was pubhshed during last 20 years. Review articles of Sitkoff et al. and Ando and coworkers summarize the apphcabihty and power of GIAO approach for study of different peptides at that time [183,184]. Today, the modem methodologies are rather oriented on appHcations of GIPAW method. As shown by Zeng... 

In papers discussed supra, GIPAW method implemented in CASTEP was exploited for computing of NMR parameters. CASTEP is commercial... 

The X-ray molecular disorder is immediately recognized by GIPAW method when experimental and theoretical shielding NMR parameters are compared. The scatter of points shown in Fig. 2.42B and C, both for tensor parameters and isotropic values exclude the drawing of acceptable linear correlation. These correlations have been greatly improved when periodic model with fuU optimization of position of heavy atoms and protons was used for calculation of GIPAW parameters. 

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