To do - dispersion features yet to be implemented

The capabilities of the relaxation dispersion analysis in relax is expansive but it cannot be called complete. There are a number of features and models yet to be implemented. Missing features include:

- The handling of off-resonance effects in the models of the numeric solution for CPMG-type data. This is specifically the `NS CPMG 2-site 3D' and `NS CPMG 2-site star' models and their `* full' equivalents. The necessary infrastructure is in place, but not activated yet (mainly due to a lack of synthetic data to test against). Currently only the software CATIA can handle this effect.
- Multi-state data - the handling of data from two sets of peaks from the same spin system is not properly supported.
It is currently handled by assuming each state is a separate spin system but this means that
*Δω*,*Δω*^{H}and related parameters are not shared as they should be. - The van't Hoff analysis of multi-temperature dispersion data (see https://en.wikipedia.org/wiki/Van_%27t_Hoff_equation).
- The Korzhnev et al. (2005b) correction for constant-time
R
_{1ρ}experiments for the analytic models ( R_{1ρ}= -*λ*_{1}-1/*T*_{relax}log*a*_{1}, where*a*_{1}= 1 -*p*_{B}cos^{2}(*θ*_{A}-*θ*_{B}), and*θ*_{A}= arctan(*ω*_{1}/*ω*_{A}) and*θ*_{B}= arctan(*ω*_{1}/*ω*_{B}). - Calculation of the dispersion
*α*value from Millet et al. (2000). - Support for CEST-type data.
- Offset support for the ground state chemical shift rather than the observed peak position.
This is really only needed for
R
_{1ρ}-type data.

If you would like one of these features, please contact the “nmr-relax-devel at lists.sourceforge.net” mailing list. The most useful would be if you have synthetic data whereby you know what the true solution should be. This can then be incorporated into a relax system test and the feature implemented to allow the test to pass. Note that such data should never be emailed to a public mailing list! Synthetic data, or experimental data, can be obtained from the literature.

Some of the missing models include:

**`TP04':**- The
R
_{1ρ}-type data Trott and Palmer (2004) N-site analytic equation for all time scales with parameters {R_{1ρ}',...,*p*_{1},...,*p*_{N},, k_{12},... k_{1N}}. **`* R**_{1ρ}':- All of the 3-site and N-site models as summarised in Table 1 of Palmer and Massi (2006).
**`BK13':**- The
R
_{1ρ}-type data Baldwin and Kay (2013) off-resonance 2-site equation for all time scales with parameters {R_{1ρ}',...,*p*_{A},*Δω*, k_{ex}}. For details and code, see the archived Gna! support request #3155. **`BK13 full':**- The
R
_{1ρ}-type data full Baldwin and Kay (2013) off-resonance 2-site equation for all time scales with parameters {R_{1ρA}', R_{1ρB}',...,*p*_{A},*Δω*, k_{ex}}. For details and code, see the archived Gna! support request #3155.

Information for how these can be added is given in the next section.

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