[QE-users] vc-relax

[Paolo Giannozzi]

On Fri, May 24, 2019 at 3:36 PM Lorenzo Paulatto <paulatz at gmail.com> wrote:


> We recently noticed that the BFGS default algorithm does not always
> respect the cell_dofree constraint, a fix is in the development verison
> of the code but not in the released version.
>

Should be present in the available patches for v.6.4.1: file
backports-6.4.1.diff
<https://github.com/QEF/q-e/releases/download/qe-6.4.1/backports-6.4.1.diff>
in https://github.com/QEF/q-e/releases

Paolo

 > thank you very much for your answer, i try it.but i set
> cell_dofree='2Dxy' , because i need to fix cell parameter. in z direct.
>

>
> As a workaround you can take the bfgs_module.f90 file from the
> development version
> https://gitlab.com/QEF/q-e/raw/develop/Modules/bfgs_module.f90
> and overwrite the one you find in Modules// and recompile the code.
>
> Or you can set
> ion_dynamics = 'damp'
> and
> cell_dynamics = "damp-pr"
> which should respect the constraint.
>
> That said, there is no specific problem to use cell_dofree='ibrav' in
> conjunction with another cell_dofree, I just implemented this feature as
> a cell_dofree value because of lazyness.
>
> You can open Modules/cell_base.f90 and at line 84 change
> LOGICAL   :: enforce_ibrav = .FALSE.! True if ibrav ...
> to
> LOGICAL   :: enforce_ibrav = .TRUE.! True if ibrav ...
> (do not forget to recompile pw.x) to use cell_dofree="ibrav" together
> with any other cell_dofree
>
> hth
>
> --
> Lorenzo Paulatto - Paris
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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