The model for no chemical exchange relaxation

This model is provided for model selection purposes. In combination with frequentist methods, such as AIC, or Bayesian methods it can show if the presence of chemical exchange is statistically significant. Optimisation is still required as one R₂⁰ value per magnetic field strength will be fit to the measured data for each spin system. If off-resonance CPMG or R_1ρ data is being used, then one of the following equations will be fit:

$\begin{subequations}\begin{align} \mathrm{R}_{\textrm{2eff}}&= \mathrm{R}_1\cos^... ...}_1\cos^2\theta + \mathrm{R}_{1\rho}'\sin^2\theta. \end{align}\end{subequations}$

The R₁ value can either be fixed to loaded experimental values or optimised. It is selected by setting the model to `No Rex'.

More information about the No Rex model is available from the:

the relax wiki at http://wiki.nmr-relax.com/No_Rex,
the API documentation at http://www.nmr-relax.com/api/3.2/target_functions.relax_disp.Dispersion-class.html#func_NOREX,
the relaxation dispersion page of the relax website at http://www.nmr-relax.com/analyses/relaxation_dispersion.html#No_Rex.

The relax user manual (PDF), created 2020-08-26.