Intersecting Two-fold Screw Axes

What would happen if you started with two intersecting two-fold screw axes?

Consider an orthorhombic cell with two two-fold screw axes.

The two screws, operating on an object, gives the following:

And one screw, operating on one of those new objects, gives yet another.

Now, fill in all the objects in the unit cell.

And locate the symmetry axes. There are the other screw axes, and in addition, a two-fold rotation axis parallel to the z axis.

This is the set of axes found in P2.

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copyright © Ron Stenkamp stenkamp@u.washington.edu Most recent update 1/17/97