Author: tlinnet Date: Tue May 6 17:35:00 2014 New Revision: 23025 URL: http://svn.gna.org/viewcvs/relax?rev=23025&view=rev Log: Added model B14 description in the manual. sr #3154: (https://gna.org/support/?3154) Implementation of Baldwin (2014) B14 model - 2-site exact solution model for all time scales. This follows the tutorial for adding relaxation dispersion models at: http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#The_relax_manual Modified: trunk/docs/latex/dispersion.tex Modified: trunk/docs/latex/dispersion.tex URL: http://svn.gna.org/viewcvs/relax/trunk/docs/latex/dispersion.tex?rev=23025&r1=23024&r2=23025&view=diff ============================================================================== --- trunk/docs/latex/dispersion.tex (original) +++ trunk/docs/latex/dispersion.tex Tue May 6 17:35:00 2014 @@ -102,6 +102,11 @@ $2*\taucpmg$ is the time between successive 180 degree pulses. Parameters are $\{\RtwozeroA, \dots, \dw, \kAB\}$. See Section~\ref{sect: dispersion: TSMFK01 model} on page~\pageref{sect: dispersion: TSMFK01 model}. + \item[`B14':]\index{relaxation dispersion!B14 model} The reduced \citet{Baldwin2014} 2-site exact solution equation for all time scales whereby the simplification $\RtwozeroA = \RtwozeroB$ is assumed. + It has the parameters $\{\Rtwozero, \dots, \pA, \dw, \kex\}$. + See Section~\ref{sect: dispersion: B14 model} on page~\pageref{sect: dispersion: B14 model}. + \item[`B14 full':]\index{relaxation dispersion!B14 full model} The full \citet{Baldwin2014} 2-site exact equation for all time scales with parameters $\{\RtwozeroA, \RtwozeroB, \dots, \pA, \dw, \kex\}$. + See Section~\ref{sect: dispersion: B14 full model} on page~\pageref{sect: dispersion: B14 full model}. \end{description} For the SQ CPMG-type experiments, the numeric models currently supported are: @@ -549,6 +554,78 @@ \item the relaxation dispersion page of the relax website at \url{http://www.nmr-relax.com/analyses/relaxation\_dispersion.html#TSMFK01}. \end{itemize} + +% Full B14 model. +%~~~~~~~~~~~~~~~~~ + +\subsection{The full B14 2-site CPMG model} +\label{sect: dispersion: B14 full model} +\index{relaxation dispersion!B14 full model|textbf} + +This is the model for 2-site exchange exact analytical derivation on all time scales (with the constraint that $\pA > \pB$), named after \citet{Baldwin2014}. +It is selected by setting the model to `B14 full'. +The equation is +\begin{equation} + R_{2,\textrm{eff}} = \frac{R_2^A+R_2^B+k_{\textrm{EX}}}{2}-\frac{N_{\textrm{CYC}}}{T_{\textrm{rel}}}\cosh{}^{-1}(v_{1c}) - \frac{1}{T_{\textrm{rel}}}\ln{\left( \frac{1+y}{2} + \frac{1-y}{2\sqrt{v_{1c}^2-1}}(v_2 + 2k_{\textrm{AB}}p_D )\right)} \\ + = R_{2,\textrm{eff}}^{\textrm{CR72}} - \frac{1}{T_{\textrm{rel}}}\ln{\left( \frac{1+y}{2} + \frac{1-y}{2\sqrt{v_{1c}^2-1}}(v_2 + 2k_{\textrm{AB}}p_D )\right)} , +\end{equation} + +where +\begin{equation} + v_{1c} = F_0\cosh{\left(\tau_{\textrm{CP}}E_0\right)}-F_2\cosh{\left(\tau_{\textrm{CP}}E_2\right)} \\ + v_{1s} = F_0\sinh{\left(\tau_{\textrm{CP}}E_0\right)}-F_2\sinh{\left(\tau_{\textrm{CP}}E_2\right)} \\ + v_{2}N = v_{1s}\left(O_B-O_A\right)+4O_B F_1^a \sinh{\left(\tau_{\textrm{CP}}E_1\right)} \\ + p_D N = v_{1s} + \left(F_1^a+F_1^b\right)\sinh{\left(\tau_{\textrm{CP}}E_1\right)}\\ + v_3 = \left( v_2^2 + 4 k_{\textrm{BA}} k_{\textrm{AB}} p_D^2 \right)^{1/2} \\ + y = \left( \frac{v_{1c}-v_3}{v_{1c}+v_3} \right)^{N_{\textrm{CYC}}} +\end{equation} + +The advantage of this code will be that you will always get the right answer provided you got 2-site exchange, in-phase magnetisation and on-resonance pulses. + +The term $$p_D$$ is based on product of the off diagonal elements in the CPMG propagator (Supplementary Section 3, \citet{Baldwin2014}). + +It is interesting to consider the region of validity of the Carver Richards result. The two results are equal when the correction is zero, which is true when + +\begin{equation} + \sqrt{v_{1c}^2-1} \approx v_2 + 2k_{\textrm{AB}}p_D +\end{equation} + +This occurs when $$k_{\textrm{AB}}p_D$$ tends to zero, and so $$v_2=v_3$$. +Setting $$k_{\textrm{AB}}p_D$$ to zero, amounts to neglecting magnetisation that starts on the ground state ensemble and end on the excited state ensemble and vice versa. +This will be a good approximation when $$p_A \gg p_B$$. +In practise, significant deviations from the Carver Richards equation can be incurred if $$p_B > 1\%$$. +Incorporation of the correction term, results in an improved description of the CPMG experiment over the Carver Richards equation \citet{CarverRichards72}. + +The reference for this equation is: +\begin{itemize} + \item \bibentry{Baldwin2014} +\end{itemize} + +More information about the B14 full model is available from: +\begin{itemize} + \item the relax wiki at \url{http://wiki.nmr-relax.com/B14\_full}, + \item the API documentation at \url{http://www.nmr-relax.com/api/3.1/lib.dispersion.B14-module.html}, + \item the relaxation dispersion page of the relax website at \url{http://www.nmr-relax.com/analyses/relaxation\_dispersion.html#B14\_full}. +\end{itemize} + + +% B14 model. +%~~~~~~~~~~~~ + +\subsection{The reduced B14 2-site CPMG model} +\label{sect: dispersion: B14 model} +\index{relaxation dispersion!B14 model|textbf} + +This is the model for 2-site exchange exact analytical derivation on all time scales (with the constraint that $\pA > \pB$), named after \citet{Baldwin2014}. +It is selected by setting the model to `B14'. +It is the same as the full B14 model described above, but with the simplification that $\RtwozeroA = \RtwozeroB$. + +More information about the B14 model is available from: +\begin{itemize} + \item the relax wiki at \url{http://wiki.nmr-relax.com/B14}, + \item the API documentation at \url{http://www.nmr-relax.com/api/3.1/lib.dispersion.B14-module.html}, + \item the relaxation dispersion page of the relax website at \url{http://www.nmr-relax.com/analyses/relaxation\_dispersion.html#B14}. +\end{itemize} % The numeric CPMG models.