The reduced CR72 2-site CPMG model

This is the model for 2-site exchange on most times scales (with the constraint that p_A > p_B), named after Carver and Richards (1972). It is selected by setting the model to `CR72'. It is the same as the full CR72 model described above, but with the simplification that R_2A⁰ = R_2B⁰. This simplifies the equations to

$${\frac{{\textrm{k}_{\textrm{ex}}}}{{2}}} \big( \big)$$ (11.27)

where D_± and η_± are unchanged and

Ψ = k_ex² - Δω², (11.28)

ζ = - 2Δω(p_Ak_ex - p_Bk_ex). (11.29)

As mentioned in the `CR72 full' model section, this model is not accurate when the motional process is very slow. In that case please use the `TSMFK01' model in Section 11.3.6 on page  instead.

More information about the CR72 model is available from:

• the relax wiki at http://wiki.nmr-relax.com/CR72,
• the API documentation at http://www.nmr-relax.com/api/3.2/lib.dispersion.cr72-module.html,
• the relaxation dispersion page of the relax website at http://www.nmr-relax.com/analyses/relaxation_dispersion.html#CR72.