No Rex

The relaxation dispersion model for no chemical exchange. This if for all SQ CPMG-type data, MMQ CPMG-type data, and R1rho-type data. This model is labelled as No Rex in relax.

Parameters

The No Rex model has the parameter R₂⁰ or R_1ρ' depending on the data type.

Equation for No Exchange in CPMG

[math] R_{2,\textrm{eff}} = R_2^0 [/math]

Equation for No Exchange in R1rho

[math] \mathrm{R}_{1\rho}= \mathrm{R}_1\cos^2\theta + \mathrm{R}_{1\rho}{´} \sin^2\theta [/math]

If no R1 values has been loaded, but the R1_fit flag has been turned on, the R1 will be fitted as well.

For on-resonance models, f.ex M61, (see also  relaxx disp.spin lock offset+field )), if [math] \bar{\Omega}_{S,i} = 0.0 [/math]

then [math] \theta = frac{\pi}{2} [/math]

and as such [math] cos^2\theta = cos^2(rac{\pi}{2}) [/math]

Reference

These is no reference for the No Rex model.

Links

The implementation of the No Rex model in relax can be seen in the:

• relax manual,
• API documentation,
• relaxation dispersion page of the relax website.