Centre of Inversion on Fourfold Axis (4 / m)


The symbol above shows a fourfold axis perpendicular to the plane of the screen, i.e parallel to Z, with a centre of inversion on the axis. This combination results when there is a mirror plane perpendicular to the fourfold axis, hence the written symbol "4 / m". A fractional value next to the symbol indicates the height of the inversion centre above the XY plane.

Although not shown, a fourfold inversion axis (-4) is also present with its inversion point at the same height as the centre of inversion.

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