[ase-users] ISIF Tag and ASE Optimizers

[Andrew Rosen]

Hi Ask,

Yes, this is what I ended up realizing as well. You have to use the
FixAtoms or filters for that case, but the optimizers don't know anything
about the ISIF tag (the VASP optimizer will, of course). Thanks.

On Tue, Oct 10, 2017 at 10:55 AM Ask Hjorth Larsen <asklarsen at gmail.com>
wrote:

> Hi Andrew,
>
> 2017-09-24 17:16 GMT+02:00 Andrew Rosen via ase-users
> <ase-users at listserv.fysik.dtu.dk>:
> > Hello ASE users,
> >
> > I am a bit confused about an aspect of the ASE optimizers. When using
> VASP
> > to optimize a structure, there is an ISIF tag that can be used to
> specify if
> > ions, cell shape, and/or cell volume are to relax. Does this ISIF tag
> have
> > any effect if one uses the ASE optimizers instead of the VASP ones? In
> > addition, what exactly does the ASE optimizers assume -- is it only
> relaxing
> > the ions (akin to ISIF = 2)?
>
> Since the calculator (which knows about input parameters like
> presumably ISIF) does not know the optimizer, the optimizer will not
> hear about an ISIF tag - I think.  Maybe someone with ASE/VASP
> knowledge can correct me if I am wrong.
>
> You can use the FixAtoms constraint to fix atoms in ASE.  ASE will by
> default optimize all atomic coordinates.
>
> Best regards
> Ask
>
> >
> > Thanks for any clarifications,
> > Andrew
> >
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>
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