This applet models the symmetry operations of the group D3h. Click on the C1 box to see the animation for the operation, a 360 degree rotation (which is equivalent to the identity operation).
The C2 is a 2-fold (180 degree) rotation that takes the triangle out of the xy- plane (the plane of the computer screen). The three dimensional effect is heightened by the inclusion of two additional atoms to the molecule in question, above and below the plane of the triangle. They appear and then disappear during the C2 rotation.
C3 is a 3-fold (120 degree) rotation in the plane. C32 is two consecutive C3 rotations, or one C3 rotation in the clockwise direction.
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 S3 rotation axis in the group D3h; 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