Full Space Group Symbol

You clicked on one of the full space-group symbols shown in red below:

P -1   For triclinic space groups the short and long forms of the space group symbol are identical.
  
P 1 21/c 1
and 
C 1 2/c 1 		For monoclinic space groups, the long form of the space-group symbol indicates the unique axis direction, which is parallel to b in this case. In this instance, the "1"s in the space group symbol indicate the absence of symmetry axes or planes with respect to the a and c directions. The full form of the space-group symbol should be contrasted with the potentially ambiguous short form.
  
P 21 21 21   For this non-centrosymmetric orthorhombic space group the short and long forms of the space group symbol are identical. Note that centrosymmetric orthorhombic space groups have both axes and planes, with both axes and planes being specified in the full form of the space-group symbol.
  
P 21/n 21/m 21/a<     By contrast, centrosymmetric orthorhombic space group, such as the one shown on the left, have both long and short forms. The short form has no ambiguity since the presence of the axes can be derived from a knowledge of the three planes given in the space group symbol.

You can return to the start page of the clickable space-group diagram that you were examining by clicking on the appropriate button below.

P-1        P21/c        P212121        C2/c       
© Copyright 1995-2006.  Birkbeck College, University of London. Author(s): Jeremy Karl Cockcroft