This is the model for 2-site exchange on all times scales (with the constraint that pA pB), named after Ishima and Torchia (1999). It is selected by setting the model to `IT99'. The equation is:
|R2eff||= R20 + Rex.||(11.32)|
The effective rotating frame field for a CPMG-type experiment is given by
|ω1eff = 4νCPMG,||(11.33)|
|ω1eff4 = 2304νCPMG4.||(11.34)|
The reference for this equation is:
More information about the IT99 model is available from:
The relax user manual (PDF), created 2019-06-14.