The data on individual symmetry operators are entered in this dialog. It is accessed only from the Operator List dialog in the Edit menu (which is also called up by the New and Open commands in the File menu).
If the type of operator is Rotation or Improper rotation, you must supply the Order of Rotation, which is an integer equal to or greater than 2. If the operator is Reflection, the order, 2, will automatically be supplied.
For a rotation axis, the Orientation is a Cartesian vector giving the orientation of the axis. For reflection, the Orientation is the vector which is perpendicular to the mirror plane.
Use the Last and Next buttons to move through the list. The Next button changes to New when you are editing the current last operator in the list.
Icosahedral position between axes... This will place a 5-fold axis (Order of Rotation must be specified as 5) in the plane containing the two Cartesian axes: the first axis should be a three-fold axis. That is, to generate the icosahedral groups, use this option to specify the 5-fold axes, and also add a three-fold axis parallel to the first Cartesian axis. No other symmetry operations need be specified - two-fold axes will be generated, as well as mirror planes if an inversion center is specified in the Operator List dialog. See Icosahedral Groups for an example.
Strictly speaking, each entry in this dialog provides one symmetry matrix, which is one symmetry operation, not an operator. However, since self-multiplication generates all the other operations belonging to each operator, this distinction is of no practical importance.