Information for point groups with fivefold rotational axis

Sometimes representations for fivefold axis are defined in terms of
Here you can find the definitions and relationships:

cos(2/5) = (5½ - 1) / 4
cos(4/5) = - (5½ + 1) / 4

= (5½ + 1) / 2

2cos(2/5) = - 1
2cos(4/5) = -

exp(i) = cos() + isin()

Last update July, 12th 2007 by A. Gelessus