The frame order theory is defined as a bridging physics theory for rigid body motions based on the statistical mechanical ordering of reference frames.
It is implemented as a new analysis type in relax designed for the study of rigid body motions in molecules.
The theory aims to unify all rotational molecular physics techniques via a single statistical mechanical molecular dynamics (MD) model, by defining a series of rank-2*n* frame order tensors.
These tensors encapsulate the maximum information content of a rotational molecular physics experiment, as well as what type of information is contained in the data.
To use the frame order theory, two steps are required:

- The physics of the experiment should be decomposed into statistically mechanically averaged product of rotation matrix elements.
- The MD model should be expressed in terms of a rotation matrix which modulates the motion of the rigid body, within the reference frame matching that of the experimental data.

The relax user manual (PDF), created 2019-03-08.