[Wien] Huge volume variation in volume optimization

[Ushma Ahuja]

Dear Wien2k users,

I am trying to work on volume optimization of a doped material, CdSiAsBi. 
The base material was CdSiAs2 and then it was doped with a bismuth atom (in a 1x1x1 supercell).
The structure thus changes from tetragonal body centred (CdSiAs2) to orthorhombic body centred (CdSiAsBi).
I tried doing the volume optimization with constant a:b:c ratio (option 1) and it took a pretty large volume percent variation to obtain an energy minimum in the energy vs. volume plot.
As can be seen from the ps file and optimize.job, I had to vary the volume upto 32% to obtain a decent curve. Somehow this much of volume variation does not look okay to me. Can I proceed with this or is there a problem with it? Is this much of volume variation okay?
I have attached the structure files, optimize.job and energy vs. vol plots for reference.

regards,

Ushma Ahuja
Faculty of Engineering
M. L. Sukhadia University
Udaipur, India
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