WIDPLT will not properly handle the type 4 profile function. Marc's
suggestion is good, but it works only for a limited set of reflections,
but not the general case. Furthermore, LY is for Cauchy (Lorentz)
broadening, this is true with the Sxx terms only when eta=1. With eta=0
this broadening is Gaussian.
A better solution would be to be able to plot the width along a preset
vector (100, 111, 531, whatever) but I have no plans to do this anytime
soon. If anyone is so inclined, they could do this themselves (the
WIDPLT code is in the gsas/expgui directory).
I seem to recall that the one-phase option in REFLIST prints a list of
reflections and their FWHM. This may be a better way to solve your
problem.
Brian
********************************************************************
Brian H. Toby, Ph.D. Leader, Crystallography Team
[EMAIL PROTECTED] NIST Center for Neutron Research, Stop 8562
voice: 301-975-4297 National Institute of Standards & Technology
FAX: 301-921-9847 Gaithersburg, MD 20899-8562
http://www.ncnr.nist.gov/xtal
********************************************************************
Xiang Ouyang wrote:
>
> Dear Marc Hostettler,
> Thank you for help.
> I should calculate FWHMxxx in the widplt (U,V,W,P,LX,LY) with Sxxx replace the LY. I
> will give it a try.
>
> Sean X. Ouyang
>
> Marc Hostettler wrote:
>
> > On Thu, 22 Mar 2001, Xiang Ouyang wrote:
> >
> > > Hello Colleagues,
> > > In GSAS CW profile #4, there are parameter U, V, W, P and LX, but no LY. how
> > > should the FWHM be calculated?
> > > I used Widplt (in Brian Toby's EXPGUI) to plot the FWHM of a pattern fit with
> > > profile #4 and the FWHM descent with 2 theta (U = 0, V = -2.3, W = 3.75, P = 0,
> > > LX = 0.8, eta = .6). Any help?
> >
> > Peak profile type no. 4 in GSAS allow to modelize anisotropic peak
> > broadening (see Stephens J.Appl.Cryst. 1999), therefore LY is parametrized
> > for each set of reflections H00, 0K0, HK0... The corresponding parameters
> > being S400, S040, S220...
> >
> > Best,
> >
> > Marc Hostettler
> > Lausanne
