[Wien] Volume optimization

[Peter Blaha]

I'd guess you have experimental "a" lattice constants and in epitaxial 
growth you want to optimize  "c"  ??? Otherwise it does not work for 
hexagonal symmetry.

It is a very difficult task: You have to edit case.struct yourself and 
change c, run a scf cycle and save.
Make another change and run another scf cycle.

Compare the energies and calculate yourself the optimal "c".

There is no "click + core-dump" button for a 1D optimization.

On 2/4/20 12:18 PM, Ali Baghizhadeh wrote:
> Dear Wien2k users
> 
> I am working on a hexagonal structure of YMnO3 epitaxial thin film. I 
> have experimental c-constant for different substrates, and I like to 
> estimate a-constant from DFT (assuming a unit cell similar to bulk one). 
> Looking at Optimize option, I could not figure out how to fix “c” and 
> relax “a”. Seems I can either optimize volume or c/a ratio or both, not 
> c or a alone. Is there any way to proceed with this calculation? Would 
> it be more rational if I relax atomic positions first, with experimental 
> c-constant and theoretical a-constant?
> 
> Thank you in advance
> 
> Ali
> 
> 
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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