[QE-users] Gw assisted relaxation calculation

[Giuseppe Mattioli]

Dear Miles
What do you mean when you say "wrong crystal structure"? Wrong atomic  
positions in a correct symmetry or wrong symmetry? Or relaxation of a  
supercell, maybe containing a defect?

This said it is in principle possible to calculate forces using GW  
(not with QE, AFAIK and I may be wrong), but in my opinion it is a  
useless bloodshed for everything but 2-atoms Si. Use EXX functionals  
(e.g., HSE06, *with norm conserving pseudopotentials*) instead, if you  
think that your GGA structure has something wrong that requires the  
correction of a delocalization error to perform relaxation.

HTH
Giuseppe

Quoting "Johnson, Miles R." <mjohnso7 at caltech.edu>:

> Hello,
>
> There are various programs which take the output of quantum espresso  
> and perform the GW approximation on top of it, but these all keep  
> whatever crystal structure parameters quantum espresso outputs. Thus  
> if the relaxation calculation from quantum espresso fails to capture  
> the correct crystal structure, the GW approximation will still  
> result in inaccurate physical properties.
>
> Is there any way in quantum espresso, or through interfacing with  
> another program, one can perform a relaxation calculation assisted  
> by the GW approximation to increase the accuracy of the final  
> crystal structure?
>
> Best,
> Miles
>
>
> Miles Johnson
> PhD Candidate in Applied Physics
> California Institute of Technology



GIUSEPPE MATTIOLI
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