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

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

aSt 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).