Calculation of NMR chemical shifts. V. The gauge invariant coupled Hartree–Fock calculation for H2O, H3O+, and OH−

Magnetic shielding constants are calculated for the hydrogens and oxygens in the isolated species of H2O, H3O+, and OH− using the coupled Hartree–Fock (CHF) method with gauge invariant atomic orbitals (GIAO). The difference from the H2O shielding is evaluated and compared with the shift relative to water in the gas phase measured experimentally. The calculated relative shift of the H3O+ protons has the same sign as the experimental result, but the shift to low field found experimentally for the OH− proton is not reproduced.