[QE-users] cell_dofree with BFGS relaxation

[Daniel Marchand]

Thanks, Lorenzo, for the rapid response. I have a bit of a concern w.r.t
the z-only relaxation. When I use BFGS the z component of all the axis are
allowed to relax. However, I do not want this, I want only the z component
of axis 3 (v3_z) to be moved, as per the description in the documentation.
This only seems possible with the damp algorithm. Here I have attached
sample input for both the bfgs and damp_pr algorithms
https://drive.google.com/file/d/17Bt8HHL55yG75cba6awvl8E_wo20KDYI/view?usp=sharing.
Perhaps I have one of the settings wrong?

Best,

Daniel


On Tue, Apr 30, 2019 at 1:07 PM Lorenzo Paulatto <paulatz at gmail.com> wrote:

> > 1) Is this still the case? When I enable this setting in my own
> > calculations (QE v6.3) I see the cell does indeed allow only
> > z-relaxation in the cell, but it does so for all the lattice directions
> > rather than just the a_3 lattice direction.
>
> In general cell_dofree works with BFGS, but it is true that some times
> damped dynamics is more reliable.
>
> I.e. I recently did some relaxations with cell_dofree="shape", as BFGS
> was not findign the minimum for some volumes, I just put
>    cell_dynamics="damp-pr"
>    ion_dynamics = 'damp'
> with everything default.
>
> cheers
>
> --
> Lorenzo Paulatto - Paris
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