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Deuterium quadrupole coupling constants were obtained for 39 sites from ab initio SCF calculations. An accuracy comparable to the experimental one is reached with a moderately large basis set of very high local quality. Comparison with experiment shows that electron correlation does not contribute substantially to this property. The experimental values for DNCO and DFCO should be reexamined, the value for CD3Cl in the literature was not properly transformed to the bond axes system, and the experimental value for ND3 agrees with the calculated one, thus showing that a dynamical model is not necessary. Several empirical relations are presented, and a simple classical model is proposed which relates the deuterium quadrupole coupling constant to the bond length with high accuracy. A theoretical study of the HCOOH dimer gives some insight into the importance of different mechanisms which lower the quadrupole coupling constant in the solid. [ABSTRACT FROM AUTHOR]

The quadrupole coupling constant and asymmetry parameter for the deuteron in liquid heavy water was determined using purely theoretical methods. Molecular-dynamics simulations with the ab initio potential-energy surface of Lie and Clementi were used to generate snapshots of the liquid. The electric-field gradient at the deuteron was then calculated for these configurations and averaged to obtain the liquid quadrupole coupling constant. At 300 K a quadrupole coupling constant of 256±5 kHz and an asymmetry parameter of 0.164±0.003 were obtained. The temperature dependence of the quadrupole coupling constant was investigated. [ABSTRACT FROM AUTHOR]