CCP14
Methods, Problems and Solutions
GSAS (General Structure Analysis System) Rietveld powder diffraction and Single Crystal software
GSAS - and DLS (Distance Least Squares) Refinement
The CCP14 Homepage is at http://www.ccp14.ac.uk
[The reference to use for GSAS in any resulting publications is:
A.C. Larson and R.B. Von Dreele, "General Structure Analysis System
(GSAS)", Los Alamos National Laboratory Report LAUR 86-748 (1994).]
GSAS - and DLS (Distance Least Squares)
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When doing DLS in GSAS, one problem you may encounter in EXPEDT
is that the " L - Least squares refinement set up" menu
option will not be available if you have turned off all the
histograms/diffraction data.
One way around for the purpose of being able to change the
least squares options is to temporarily enabled a Histogram;
then disable it again prior to performing the DLS.
Bob von Dreele also suggests a short cut for doing this below:
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Date: Mon, 05 Feb 2001 08:51:33 -0700
To: "L. Cranswick"
From: vondreele@lanl.gov (Bob Von Dreele)
Subject: Re: GSAS and DLS
Dear Lachlan,
It's neat that "DLS" works - I had tried it several years ago with
distances & a dummy diffraction pattern. Your problem (feature) is the way
expedt is supposed to work. Hope you don't mind switching use of that
histogram back & forth. If you look at the exp file at the record with
"HTYPn"; the "*" says don't use this histogram & " " to use it. Since
changing it in expedt & getting at the L-S stuff is awkward - it might be
easier for you to change it by hand.
Bob
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