[QE-users] cell_dofree with BFGS relaxation

[Daniel Marchand]

Hi QE community,

I would like to do a vc-relax with freedom only in the 'z-direction'. i.e.
a calculation with:
cell_dofree = 'z'

My understanding was that as of (2009) cell_dofree was not supported for
bfgs reaxation.
http://www.democritos.it/pipermail/pw_forum/2009-August/013979.html

I had the following questions/comments:

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.

2) If cell_dofree is not supported with bfgs, may I request the
documentation be updated to reflect this?

3) When I use cell_dynamics='damp-pr', the code does what I want (at least
w.r.t to cell-relaxation). Is it at all appropriate to use 'damp-pr' for a
cell minimization, or is it strictly for MD runs?

Best,

Daniel Marchand, Doctoral Candidate, EPFL LAMMM
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