Calculation of the hydrogen-bond NMR shift in the water dimer

The shielding constant of the hydrogen-bonded proton in the linear perpendicular water dimer is calculated from the SCF MO LCGO wavefunction unsing the uncoupled Hartree-Fock variation-perturbation procedure of Karplus and Kolker. The obtained result (27.61 ppm) is compared with the experimental estimate of the proton shielding in the liquid water (25.62 ppm). Comparing with the proton shielding in the water molecule, calculated previously within the same approximation (28.30 ppm), the non-empirical hydrogen-bond shift of −0.69 ppm is found.