Hydrogen chemical shieldings in small molecules: a magnetic field density functional approach

Three approximations to the isotropic chemical shielding functional are used to calculate isotropic hydrogen chemical shieldings in small molecules. The approximations, at most, require the electron density and its angular derivative at the hydrogen nucleus. Results are compared to a variety of theoretical calculations and/or experiments. Deviations from these calculations are at worst off by 40%, and at best off by a few percent.