short communications
Tables of alphanumeric data concerning crystals twinned by merohedry are presented, assembled into a spreadsheet. The twin table is structured on the 230 space groups and contains the following information: centrosymmetric/chiral indicator, polar axes, twin index, twin operators, some physical property relations, symmetry-related reflections, inversion techniques and a pointer to software use. The software table contains the preceding information translated into command lines for SHELXL [Sheldrick (2008). Acta Cryst. A64, 112-122]. The macromolecular table contains a reduced form of the twin table applicable to enantiomerically pure compounds of known absolute configuration.
Keywords: twinning; spreadsheets; refinement; chirality; noncentrosymmetry; inversion; polarity; physical properties; SHELXL; absolute structure.
Supporting information
Portable Document Format (PDF) file https://doi.org/10.1107/S0021889812044974/nb5039sup1.pdf |