Fourfold Axis (4)


The symbol above shows a fourfold axis perpendicular to the plane of the screen, i.e parallel to Z. A fourfold axis is equivalent to an anticlockwise rotation of 90° about a line. A fourfold rotation about the c-axis, i.e. about the line 0,0,z, will have the corresponding symmetry operator -y,x,z. This axis has the written symbol "4".
In space group diagrams for cubic symmetry, fourfold axes are shown along both X and Y directions as well as along the Z direction when present. The symbol for these is shown above.

© Copyright 1995-2006.  Birkbeck College, University of London. Author(s): Jeremy Karl Cockcroft