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CCP14

Tutorials and Examples

Peak Fitting using Xfit-Koalariet (Coelho and Cheary) for Win95/NT

Constraining Peak Widths

The CCP14 Homepage is at http://www.ccp14.ac.uk

[Tutorials page] | [XFIT Tutorial Index]

[The reference to use for XFIT or FOURYA in any resulting publications is: Cheary, R. W. & Coelho, A. A. (1996). Programs XFIT and FOURYA, deposited in CCP14 Powder Diffraction Library, Engineering and Physical Sciences Research Council, Daresbury Laboratory, Warrington, England. (http://www.ccp14.ac.uk/tutorial/xfit-95/xfit.htm)]

The Problem

Following is an example using simulated data showing how with unconstrained peak widths, you can get a variety of results. But with peak-widths constrained to be the same values, results more consistent with the true values.

In this case the datasets consists of the following, but we will only dot his on widths\3010.xdd:

The two PV peaks has the following values:

pk1: 
  area = 100
  th2 = 30
  FWHM = 0.2
  PV-lortz = 0.5

pk2: 
  area = 100
  th2 = 30.1 for 3010.xdd, 30.15 for 3015.xdd 
                       and 30.20 for 3002.xdd
  FWHM = 0.2
  PV-lortz = 0.5


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