Hi, Unfortunately, there is no ability to fix one of the model-free parameters during optimisation in relax yet. This is something that has been requested one or two times over the years. This is complicated as the gradients and Hessians (first and second partial derivates) need to be modified with this in mind, as the curvature of the space changes. The fixed parameter is not part of the gradient or Hessian, and has to be removed. This really complicates the target function, gradient, and Hessian and, due to the low demand, has not been implemented.
Are you able to optimise this parameter and see if you get 0.111? And are you able to extract the timescale of this process (the methyl group rotamer jumps)? From memory, someone has optimsed these models using a grid search. This coarse optimisation can be performed in relax as you are able to specify the fine details of the grid search. It is slower, but will do the job. You could even implement a zooming grid search if your scripting skills are up to it to be able to relatively quickly find the parameters to high precision. Anyway, I hope this info helps. Regards, Edward On 6 April 2011 17:39, Tiago Pais <[email protected]> wrote: > Hi, > > I would like to make an analysis of side-chain relaxation data with the S2f > parameter (in model 5) set to 0.111. > > Is it possible to do this with RELAX? How? > > Thanks in advance. > > Cheers > > Tiago P > > > > ************************************** > > Tiago Pais, PhD. student > > Cell Physiology & NMR > > Instituto de Tecnologia Química e Biológica-Oeiras > > > > __________ Information from ESET NOD32 Antivirus, version of virus signature > database 6019 (20110406) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > _______________________________________________ > relax (http://nmr-relax.com) > > This is the relax-users mailing list > [email protected] > > To unsubscribe from this list, get a password > reminder, or change your subscription options, > visit the list information page at > https://mail.gna.org/listinfo/relax-users > > _______________________________________________ relax (http://nmr-relax.com) This is the relax-users mailing list [email protected] To unsubscribe from this list, get a password reminder, or change your subscription options, visit the list information page at https://mail.gna.org/listinfo/relax-users
