Spatial Distribution of O-H ... O Systems in Inorganic Crystals: A Distance Correction and a Visualization Method

In this paper, a color contour map in polar coordinate system was exploited to visualize the spatial distribution of O-H ... O systems in inorganic structures derived from Inorganic Crystal Structure Database. The frequency distribution of H ... O distances for O-H ... O systems has been normalized properly to exclude the pure geometric influence on the statistics. Combining with the well-accepted "cone correction" which scales the angular distribution, an exact spatial distribution of O-H ... O systems was successfully obtained. The visualization of such a spatial distribution was realized in a color contour map by introducing an S-type function to transform the detected number into a relative probability so that the detailed information of the distribution can be clearly illustrated. The orientation and distances preferences of O-H ... O hydrogen bonds and non-bonding arrangements were clearly shown in the color contour map. It is believed that both of the distance correction and the visualization method can be useful to the statistical analysis of various kinds of D-H ... A systems, where D= O, N, C etc. and A = F, Cl, Br, N etc. both in inorganic-and organic-crystals.