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 = - λ₁ -1/T_relaxloga₁, where a₁ = 1 - p_Bcos²(θ_A - θ_B), and θ_A = arctan(ω₁/ω_A) and θ_B = arctan(ω₁/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',..., p₁,..., p_N,$\overline{{\omega}}$, k₁₂,... 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.