If your refinement looks good it doesn't necessarily mean your model is true, just that you have a lot of parameters :-)
Negative temperature factors mean that your refinement is trying to add intensity at high angles, the opposite of the temperature effect. This may mean that you haven't corrected for absorption, which for small values is the equivalent of an overall negative temperature - eg see: factor http://scripts.iucr.org/cgi-bin/paper?a16955 Unfortunately there is an error of a factor of two in that paper :-) Alan On 1 November 2014 19:08, Rachid Abkar <rachid.ab...@gmail.com> wrote: > The Biso isotropic displacement parameter of each element in my refinement > using fullprof is over 3 and negative ? but my refinement looks good and > Rwp is only 9 could anybody give me some advice Thanks sincerely > > *ABKAR RACHID* > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Please do NOT attach files to the whole list <alan.he...@neutronoptics.com > > > Send commands to <lists...@ill.fr> eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://www.mail-archive.com/rietveld_l@ill.fr/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > -- ______________________________________________ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * <alan.he...@neutronoptics.com> +33.476.98.41.68 http://www.NeutronOptics.com/hewat ______________________________________________
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
