Non-linearity of hydrogen bonds in molecular crystals

IN recent studies of the non-linearity of hydrogen bonds 1,2 , histograms have been shown of the O–H ⋯ O angles, ψ The distributions reflect the energy dependence of the hydrogen bond on the angle ψ . In such distributions maxima are found at values of ψ approximately 15° from the linear configuration. Model calculations on water dimer interactions 3 indicate, however, that the configuration of minimum energy involves a linear hydrogen bond.