Oxygen chemical shielding

Figure 7. Plots of the calculated oxygen chemical shielding using the FPT-MNDO-PM3 method against the hydrogen bond length.

The chemical shieldings were then recalculated in this same system using the QM/MM method [10], To this end, each molecule was considered individually. The water molecule of interest and its first solvation shell were treated quantum mechanically, whereas the surrounding water molecules were taken into account with an empirical force field representation (MM molecules). The first solvation shell was defined via a distance criterion on the oxygen-oxygen distance. As a threshold, the first minimum of the O-O pair correlation function was taken this occurs at 3.5 A [93]. All... 

The direction of the principal axes of the electric field gradient tensor and the chemical shielding tensor of the carboyl oxygen... 

K. Yamada, S. Dong, G. Wn, A solid-state NMR investigation of the carbonyl oxygen electric-field-gradient tensor and chemical shielding tensor in amides, J. Am. Chem. Soc. 122 (2000) 11602. 

R. E. Wasylishen, S. Mooibroek, and J. B. Macdonald, /. Chem. Phys., 81, 1057 (1984). A More Reliable Oxygen-17 Absolute Chemical Shielding Scale. 

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