International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

© International Union of Crystallography 2006
International Tables for Crystallography (2006). Vol. C. ch. 9.7, pp. 897-906
https://doi.org/10.1107/97809553602060000623

Chapter 9.7. The space-group distribution of molecular organic structures

A. J. C. Wilson,a‡ V. L. Karenb and A. Mighellb

a St John's College, Cambridge CB2 1TP, England, and bNIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA

Footnotes

‡ Deceased.

1 Names in Cyrillic characters are transliterated in many ways in non-Russian languages. In this chapter, `Kitajgorodskij' is used throughout the text, but the source transliteration is retained in the list of references. Similar complications arise with other names in Cyrillic characters.
2 The US translation (Kitajgorodskij, 1961[link]) differs from the original in several respects. Only relevant differences are noted in this chapter.
3 Empirically, only dimers involving a centre of symmetry or a diad axis are important in the systems under consideration. In principle, n-mers involving any point-group symmetry could be formed.
4 Table 4.3.1 is not strictly consistent in its treatment of the `extended' symbols. Tetragonal space groups are extended in full detail, but the extension of orthorhombic space groups is minimal.
5 Such counts are tedious and subject to error, but the table should be correct within a few units.
6 Statistical modelling programs distinguish between variates and factors. The values of variates are ordinary numbers; [2], [m], [\ldots] are variates. Factors are qualitative. In the immediate context, `arithmetic crystal class' is a factor, but other categories, such as metal-organic compound, polypeptide, structural class (Belsky & Zorky, 1977[link]), [\ldots], could be included if desired. The programs allow appropriately for both variates and factors; see Baker & Nelder (1978[link], Sections 1.2.1, 8.5.2, 22.1 and 22.2.1).