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International
Tables for Crystallography Volume F Crystallography of biological macromolecules Edited by M. G. Rossmann and E. Arnold © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. F. ch. 22.1, p. 541
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Structures of macromolecules determined by X-ray crystallography rarely reveal the positions of the hydrogen atoms. It is, of course, possible to add explicit hydrogen atoms at the stereochemically most likely positions, but this is rarely done for surface-area calculations. Instead, their average effect is approximately and implicitly accounted for by increasing the heteroatom van der Waals radius by 0.1 to 0.3 Å. (It is not usual to smear atoms to account for thermal motion.)
