This applet models the symmetry operations of the group D4h, the square with center. 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.
"i" is the inversion operation, which copies an atom through a central point (the center) onto the other side.
There is also a S4 rotation axis in the group D4h; no animation for it has yet been added to the applet.
The central atom of the complex is red, to demonstrate that it is different from the atoms on the corners, which are identical to each other. This represents the very common square planar complexes of metals, where the metal is the red sphere, and its ligands are the blue spheres.
© 2003-2011 by Lawrence T. Sein. All rights reserved.
Send questions to: lseinjr@hotmail.com