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Remarkable features in lattice-parameter ratios of crystals. I. Orthorhombic, tetragonal and hexagonal crystals; II. Monoclinic and triclinic crystals

Acta Cryst. (2005). B61, 287–295; 296–303

[Lattice-parameter ratios] Frequency distribution of orthorhombic inorganic crystals as a function of c/b (in red). All important peaks correspond to integral lattices.
The basic features of frequency distribution as a function of lattice-parameter ratios are reported. Observed are exponential decay evidenced by increasing ratios and sharp peaks, possibly due to integral lattices, with one of the most important peaks at the ratio 1:1. Most of these features do not follow from classical crystallographic principles. Some of these properties can be interpreted on the basis of a general crystallography, where crystallographic scaling is considered. These results are compatible with crystallographic properties observed in a number of axial-symmetric proteins. 
R. de Gelder and A. Janner