[CP2K-user] [CP2K:12477] space group

[Pierre-André Cazade]

Dear Juerg,

I have been working in implementing the space group symmetry but I am a bit 
confused by the content of the x0 and g vectors as found in the subroutine 
geoopt_bfgs in the file bfgs_optimizer.F. From the various calls and 
manipulation of these vectors, I get they contained the 3*NATOM 
coordinates/forces of the system. Furthermore, they can contain the 
coordinates/forces for shells. There are also extra content which I assume 
are the unit cell parameters and the associated gradient. However, it is 
unclear where this extra information is located. From the various part of 
the code I read, I am under the impression that the cell gradient is 
located at the end of the g vector while the cell parameters are at the 
beginning of the x0 vector. I know this to be wrong due to various prints I 
have made and from how geoopt_bfgs works. Yet pieces of code like the one 
that follows (found in gopt_f77_methods.F) do not help making it clear:

IF (master == para_env%mepos) THEN ! we are on the master
               CPASSERT(ASSOCIATED(gradient))
               nparticle = force_env_get_nparticle(gopt_env%force_env)
               nsize = 3*nparticle
               CPASSERT((SIZE(gradient) == nsize+6))
               CALL pack_subsys_particles(subsys=subsys, 
f=gradient(1:nsize), fscale=-1.0_dp)
               CALL apply_cell_change(gopt_env, cell, gradient, 
update_forces=.TRUE.)
               cell_gradient => gradient(nsize+1:nsize+6)

Would you have a summary of what to find each of these arrays depending on 
the type of calculation/options requested?

Many thanks,
Pierre


On Friday, November 8, 2019 at 8:31:32 AM UTC, jgh wrote:
>
> Hi 
>
> point group / space group constraints are not possible. 
>
> regards 
>
> Juerg Hutter 
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: h... at chem.uzh.ch 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----c... at googlegroups.com <javascript:> wrote: ----- 
> To: "cp2k" <c... at googlegroups.com <javascript:>> 
> From: "Pierre-André Cazade" 
> Sent by: c... at googlegroups.com <javascript:> 
> Date: 11/07/2019 05:35PM 
> Subject: [CP2K:12477] space group 
>
> Dear users, 
>
> Is there a way to conserve/constraint the space group of crystal when 
> performing a CELL_OPT in the same way we can constraint the lattice system 
> with the keywords KEEP_SYMMETRY  and KEEP_ANGLES? 
>
> Many thanks, 
> Pierre   
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