[Wien] Volume optimization to monoclinic structure

[Víctor Luaña Cabal]

On Tue, May 08, 2018 at 06:22:25AM -0600, Gavin Abo wrote:
> Currently, I believe parabolfit_lapw is the best way available at this  
> time.  I'm not currently aware of any better fitting methods. If you  
> find a better way, feel free to share.

I don't even know parabolfit_lapw, but I ever try the simplest tool
available, and the non linear fitting tool of gnuplot works for almost
anything. You create first a data file

# comment
# data description
# var1   var2   var3  function
#   a      b      c       E
  1.234  1.342  1.785  -764.456
.....

then create in gnuplot the mathematical description of the f(v1,v2,v3)
and then, ggain in gnuplot
E(V,k1,k2,k3) = ......

fit f(x,y,z) 'datafile' using ($1*$2*$3):4 via  k1,k2,k3

whithin gnuplot a 'help fit' will provide you a detailed description
and examples.

It will not be the best method but an all-purpose tool.

Best regards,
             Víctor Luaña
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