The effects of vibration-rotation on the quadrupole moment, rotational g-factor and spin-rotation parameters of the water molecule

Ab initio SCF surfaces for the quadrupole moment, rotational g-factor and spin-rotation parameters of the water molecule have been obtained from the magnetizability and nuclear shielding surfaces. Values of these properties in low vibration-rotation states of the more important isotopomers are presented. Vibrational averaging (with an accurate empirical force field) brings calculated values to within 1 per cent of experimental values for the quadrupole moment components and 3 per cent for the g-tensor components. Substantial vibrational effects on the proton, deuteron and 17O spin-rotation parameters are predicted but the calculated values differ significantly from experiment. This is attributed to inadequacy of the SCF calculation of paramagnetic shielding.