The modelling of motion in molecules using experimental data consists of either continuous or discrete distributions. These can be visualised respectively as either an infinite number of states or a limited set of N states. The N-state model analysis in relax models the molecular dynamics using an ensemble of static structures.

This analysis supports a number of data types including:

The main idea is to evaluate the quality of a fixed ensemble of structures. relax will not perform structural optimisations. The evaluation includes:

- Alignment tensor optimisation for the RDCs and PCSs.
- Optional optimisation of the position of the paramagnetic centre for the PCSs.
- Calculation of NOE constraint violations.
- Q factor calculation for the RDC, PCS, and NOE.

Note that this analysis will also handle single structures. Hence you can use the N-state model in relax with N set to 1 to find, for example, a single alignment tensor for a single structure using RDCs, PCSs, or both together. This is useful for comparing a ensemble to a single structure to determine if any statistically significant motions are present.

The primary references for the N-state model analysis in relax are:

The relax user manual (PDF), created 2019-06-14.