This applet models the symmetry operations of the group D4h, the square. Click on the C1 box to see the animation for the operation, a 360 degree rotation (which is equivalent to the identity operation).
There are three different C2 2-fold (180 degree) rotations in this group.
C4 is a 4-fold (90 degree) rotation in the plane.
The letter σ represents a mirror plane, which reflects one part of the molecular into the other half. σh is the horizontal mirror plane, in the plane of the screen - it reflects the top half of each atom into its bottom half. σv is the vertical mirror plane, perpendicular to the plane of the computer screen. It reflects the right half of the equilateral triangle into the left, reflecting the right half of atom 1 into the left half of 1. Yellow color is used to suggest a reflective glass.
There is also a S4 rotation axis in the group D4h; no animation for it has yet been added to the applet.
© 2003-2011 by Lawrence T. Sein. All rights reserved.
Send questions to: lseinjr@hotmail.com