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Lattice parameters (Volume or c/a)

The auxilliary program optimize (x optimize) helps you to find the equillibrium volume or c/a ratio. It generates from an already existing case.struct or case_initial.struct a series of struct files with various volumes (c/a ratios) (depending on your input) and a shell-script optimize.job which looks similar to:

#!/bin/csh -f
 foreach i ( \
        tic_vol_-10.0  \
        tic_vol__-5.0  \
        tic_vol___0.0  \
        tic_vol___5.0  \
        tic_vol__10.0  \
 )
     cp  $i.struct tic.struct
 #    cp  $i.clmsum tic.clmsum
 #    x dstart
     run_lapw -ec 0.0001
     set stat = $status
     if ($stat) then
        echo "ERROR status in" $i
        exit 1
     endif
     save_lapw  $i
 end

You may modify this script according to your needs (use runsp_lapw or even min_lapw, specify different convergence parameters, save into a directory to separate e.g. ``gga'' and ``lda'' results, activate the line ``x dstart'' or `` cp $i.clmsum case.clmsum'' to use a previously saved clmsum file, e.g. from a calculation with reduced RKmax, ...)

Note: You must have a case.clmsum file (either from init_lapw or from a previous scf calculation) in order to run optimize.job.

Using the script grepline (or the ``Analysis Analyze multiple SCF-files'' menu of WIEN in a BOX) you get a summary of the total energy vs. volume (c/a). The file case.analysis can be used in eplot_lapw or any other xy-plotting program to find the minimum total energy and the equilibrium volume (c/a).

grepline :ENE '*.scf' 1 > case.analysis

Using such strategies also more-dimensional optimizations (e.g. c/a ratio and volume) are possible in combination with the -d option of save_lapw.

begin:min


next up previous contents
Next: Minimization of internal parameters Up: Structure optimization Previous: Structure optimization

2000-04-11