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Dear Dirk,<br>
<br>
Thank you for your answer. I went through the tutorial about CUTOFF
and RELCUTOFF. That's how I came up with CUTOFF=1400 and
RELCUTOFF=80. I also tried CUTOFF=400 and RELCUTOFF=60. It does not
change the problem when it comes to the cell optimization.
Furthermore, I have, to some extend, a similar issue on the large
crystal using DFTB. Please have a look at the input files, there
might be a silly mistake I make or a missing keyword, I am not aware
of.<br>
<br>
Regarding the tutorial, it is far from being helpful as the
criterion to decide if CUTOFF and RELCUTOFF are appropriate is
rather undefined/unspecific. Anyway, I have exhausted the resources
available on CP2K website before asking on the forum.<br>
<br>
Thanks again,<br>
Pierre<br>
<br>
<div class="moz-cite-prefix">On 07/08/2019 17:26, Dr. Dirk
Buddensiek wrote:<br>
</div>
<blockquote type="cite"
cite="mid:f1e0de7d-31e9-4d...@googlegroups.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div>Dear Pierre,</div>
<div>at first glance the CUTOFF and RELCUTOFF seem to be a lttle
bit unbalanced. Maybe it would help to take a look in the
tutorial hpw to get optimised cuttof
values. <a class="moz-txt-link-freetext" href="https://www.cp2k.org/howto:converging_cutoff">https://www.cp2k.org/howto:converging_cutoff</a></div>
<br>
Am Mittwoch, 7. August 2019 17:05:56 UTC+2 schrieb Pierre-André
Cazade:
<blockquote class="gmail_quote" style="margin: 0;margin-left:
0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;">
<div dir="ltr">Hello,
<div><br>
</div>
<div>I am rather new to CP2K though I am experienced with
molecular modelling both quantum and classical, and with a
wide range of software. It is quite frustrating that it
seems impossible to get CP2K to perform a simple CELL_OPT
of a beta glycine crystal (20 atoms, monoclinic) with PBE.
Such a calculation works fine with VASP, so I am quite
surprised the same calculation goes astray with CP2K.
Basically, the B unit cell vector increases drastically up
to absurd values. Needless to say, this is a test system
as I wish to use CP2K for its linear scaling DFT to model
protein crystals. I have tried to play with CUTOFF and
REL_CUTOFF in the MGRID section up to 1400 and 80
respectively. I also tried GPW and GAPW methods, all
electrons or GTH pseudo. Nothing works. Please, if anyone
could have a look at the attached input file
"cell_opt_qm.inp" and point what's wrong in it, I would be
grateful.</div>
<div><br>
</div>
<div>Furthermore, I have tried LS approach with DFTB on a
5x5x5 crystal of beta glycine and do not have much more
success. First, the pressure in the crystal is insanely
high and will lead again to a 20 folds increase of the
lattice vectors (with CG). Then, with LBFGS method, the
system stops after 3 to 4 cycles with a message telling
LBFGS convergence criteria were reached, whereas the
system is clearly not. Again, I would be grateful if
anyone could tell me what's wrong with my system
("cell_opt2_qm.inp" with "betacry.pdb" for the
coordinates). Ideally, my goal would be to be able to run
large complex systems with the LS approach and with any
DFT/DFTB method.</div>
<div><br>
</div>
<div>Thank you in advance for your help.</div>
<div><br>
</div>
<div>Regards,</div>
<div>Pierre</div>
</div>
</blockquote>
</div>
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<br>
<pre class="moz-signature" cols="72">--
Dr Pierre Cazade, PhD
AD3-023, Bernal Institute,
University of Limerick,
Plassey Park Road,
Castletroy, co. Limerick,
Ireland</pre>
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