Calculation Control

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BGMN Control File

The Rietveld calculation with BGMN is controlled by a simple text file with the file extension 'sav'.

By means of the control file for the plaster sample (plaster.sav) the necessary elements will be explained here. Please open BGMNwin and select
File→Open Control File,
browse to the PLASTER\plaster.sav file and open it:

plastersav.png

For an extended explanation of a variable put the cursor of your BGMNwin window to that variable and press F1 or see a list of variables.

First, the instrumental function has to be provided: 

VERZERR=urdneu11.geq
Then the pattern data file is needed: 
VAL[1]=kldomei5.val

This file is in the APX-63 format, a simple text format from the SEIFERT-FPM diffractometers. Also, BGMN can process files with the extension 'rd' (Philips APD) and 'raw' (SIEMENS Diffrac-AT) and two variants of 'gsa' (GSAS) as well. If you want to use other formats, you have to convert it into one of the above.

If a secondary graphite monochromator was used, an appropriate polarisation factor is (26.6° is the 2Θ angle of the graphite crystal; without monochromator use 'POL=1', which is the default): 

pi=2*acos(0)
POL=sqr(cos(26.6*pi/180))
The structure files are given in this way: 
STRUC[1]=quartz.str
STRUC[2]=calcite.str
STRUC[3]=gypsum.str
And the formulae for the quantitative analysis are: 
GOAL[1]=quartz/(quartz+calcite+gypsum)
GOAL[2]=calcite/(quartz+calcite+gypsum)
GOAL[3]=gypsum/(quartz+calcite+gypsum)
In this file (plaster.lst) the results are written: 
LIST=plaster.lst
An output file for the peak list (plaster.par) is necessary if you want a peak list: 
OUTPUT=plaster.par
For the easy inspection of diagrams a file (plaster.dia) with pattern, calculated, difference and background data can be written: 
DIAGRAMM=plaster.dia
Last, the global parameters for the zero point (EPS1) and sample displacement (EPS2) are included: 
PARAM[1]=EPS1=0_-0.0001^0.0001
PARAM[2]=EPS2=0
Select 
PROTOKOLL=Y
to get more information about the refinement progress.

If you made any changes to plaster.sav, please save it. The calculation is started by the command
Run→BGMN
Browse to the plaster.sav file and open it, and after each iteration step a line with information about the iteration number, the least squares sum and some other values is printed.

Structure Output Files

If one wants to inspect/process the resulting structure(s), three structure formats can be written: The above mentioned statements have to be included in the BGMN control file for each structure.

For further output see Result Output