6 The post-processing program plot

Many of the files created by one of the SPRKKR programs may be further processed using the program plot, as for example the files DATASET.dos containing the component, spin and angular momentum resolved DOS. These files can be fed directly to plot by calling:

plot < Fe.dos

A keyword in the first line of the data file tells plot how to interprete and process the data. As a results one gets a number of plot files (*.agr) that can be viewed, further processed and printed using xmgrace. xmgrace allows in particular to read in addition experimental data from other files that can be compared with the theoretical results.

Often it is necessary to supply plot with additional parameters to control the post-processing. This can be achieved by calling plot for example:

plot < Fe.dos.pin

with a control file Fe.dos.pin that may look like this:

DATASET Fe_DOS.dos

# remove leading # of sections and parameters to activate and insert values

For this control file the same rules as for the SPRKKR input files apply (see chapter 2), with the available sections listed below.

section DATASET

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This information is obligatory if a control file is used. In this case plot reads first the control file and then opens the dataset file to read the data.

For most dataset file type plot ignores these variables in the control file and sets the energy range to be plotted according to the supplied data. Use xmgrace in this case to set the energy rangy.

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The program plot is part of the xband package. It is therefore most convenient to run plot via xband. xband allows to pass the data file directly to plot and to create the appropriate xmgrace files that way (left mouse click). Alternatively, one can invoke a menu that asks for the parameters given above (middle mouse klick) to create a control file first and then the xmgrace files. Because xband reads the keyword from the data file, the menu asks only for specific parameters.

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7 Examples

The following example gives you a short introduction how to use the SPRKKR-package in connection with xband. It is assumed that you installed xband and that the programs kkrscf and kkrgen are compiled (see 8.1) and copied to your directory ˜/bin.

Start xband.

Click CREATE SYSTEM .

Click Structure type .

Select BCC by mouse click.

Insert 5:4 in the entry field for a.

Click CONFIRM .

Click input OK – GO ON .

Click all done – RETURN .

Click the line

You have now created the system file Fe.sys that is listed on the info screen.

Click SPR-KKR to continue.

Click create input .

Click the scf button in the TASK field (left column).

Click write inpfile quit .

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This step created the input file Fe SCF.inp together with a potential file Fe.pot, that contains enough information to start the SCF calculations.

If you press write+edit inpfile quit instead, the editor is invoked and you may check or modify the input file.

Click kkrscf to invoke the menu and select run (interactive). This starts in a separate yellow xterm window the kkrscf program. While the program runs, you may check its progress by clicking out-file menu and selecting grep ”ERR” Fe SCF.out. After kkrscf completed successfully you may destroy the yellow window – the output is kept in Fe SCF.out.

The converged potential is now stored in Fe.pot new. Click files and select Fe.pot new. Change the file name in the entry field (right bottom) to Fe.pot and click move to move Fe.pot new to Fe.pot. This step is done because the default name for the potential file is

Fe.pot.

This step creates the input file Fe DOS.inp for a DOS calculation.

Click kkrgen and select file run (interactive) option. As before kkrgen runs in a yellow xterm window and writes output simultaneously to Fe DOS.out. In addition a data file Fe DOS.dos will be created.

Click plot to invoke the plot menu. Select Fe DOS.dos in the datafile list by left mouse click. This invokes the program plot that creates a file Fe DOS.dos Fe.agr listed in the right file column. Select this file by left mouse click. This last step invokes the graphics program xmgrace that should now display the spin-resolved DOS of bcc-Fe.

Further examples for the use of the SPRKKR-package can be downloaded from http://olymp.cup.uni-muenchen.de/ak/ebert/SPRKKR/examples.html. The downloaded file has to be unpacked using gunzip and tar. It contains a postscript file describing a number of applications of the SPRKKR-package with the corresponding input and output files included. More information can be found in the enclosed README-file.

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