[Wien] Query regarding structure optimization

[Peter Blaha]

YES ! Force optimization is MUCH more important than anything else. 
Lattice parameters are usually well known from experiment (and more 
accurate than DFT), but atomic positions are often NOT well known 
experimentally.

Exception: Some structures like NaCl have "fixed positions by symmetry". 
So you have to find out yourself, if you have forces.

How to do:   Simply edit optimize.job and activate the -min switch in 
the run_lapw line.

ad 2): If your minimum is close enough to one of your relaxed structures: no
However, whenever you change a,b or c, do a force optimization.

On 6/21/20 9:01 AM, shamik chakrabarti wrote:
> Dear Wien2k users,
> 
>         I have two queries;
> 
> (1) Should we have to do force minimization *simultaneously* for each 
> step (a) V optimization, (b) c/a optimization, (c) b/a optimization for 
> a orthorhombic crystal?
> 
> (2) After a, b, c optimization should we have to do force minimization 
> again? (I think yes!)
> 
> with regards,
> 
> -- 
> Dr. Shamik Chakrabarti
> Research Fellow
> Department of Physics
> Indian Institute of Technology Patna
> Bihta-801103
> Patna
> Bihar, India
> 
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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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Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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