CALCULATION OF NUCLEAR MAGNETIC SHIELDINGS .8. GAUGE INVARIANT MANY-BODY PERTURBATION METHOD

The calculation of nuclear magnetic shieldings sigma was performed for four first-row hydrides, i.e., HF, H2O, NH3, and CH4 using the finite-field many-body perturbation theory through second order in the electron correlation correction with London's gauge invariant atomic orbitals. The calculated isotropic shieldings sigmaBAR for the heavy atoms were larger than the experimental values. The rotational and vibrational correction for the sigmaBAR of the F atom in HF at 300 K was estimated to be -4.0 ppm.