Hydrogen bonds and (hyper)polarizabilities in molecular crystals: An ab initio SCF study of urea

Ab initio SCF calculations of the (hyper)polarizability tensors of the urea molecule and of selected hydrogen-bonded dimers and trimers of urea are reported, using an extended basis set, with an eye toward accounting for the optical properties of crystals made up of molecular structures associated through hydrogen bonds. It is found that the additivity relationship holds well for ᾱ and γ̄ even though some individual components are enhanced significantly in the clusters, while other components show the effect of destructive interference from the neighboring units.