http://proteopedia.org/wiki/images/7/76/Wobble.spt
jmol script to move molecule around a given orientation in a precession movement.
Preliminaries
A quaternion is an mathematical object (like a matrix or a complex number) with four parameters x y z w. It is useful to express orientations and rotations, and to do calculations (combining, interpolating, dissecting) on them.
Jmol shows structures (e.g. atom positions) on a display and allows the view to be rotated and individual atomic positions to be manipulated. The atoms have Cartesian coordinates x, y, z, and when you rotate the model, the coordinate system is rotated (same coordinates x, y, z, but axes of coordinate system point in different directions).
Combining two rotations
Interpolating between orientations
Interpreting a rotation
