[CP2K-user] [CP2K:11946] Ionic crystals with GFN-xTB

hut... at chem.uzh.ch hut... at chem.uzh.ch
Thu Jul 4 16:01:38 CET 2019


Hi

we also found that xTB is rather unstable for some systems/atom types.
We think this is mainly due the 3rd order Coulomb term and the
value of gamma (its proportionality factor).
Currently, I don't have an easy solution ready. In your case I would
start with some test calculations on the simple molecules, e.g. CaF2.
You can then try to re-parameterize the atoms (or just the metal?).
You can add the parameters to the input file (see examples in the regtests)
for easy changes.

regards

Juerg
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "mpol" 
Sent by: cp... at googlegroups.com
Date: 07/04/2019 10:57AM
Subject: [CP2K:11946] Ionic crystals with GFN-xTB

Dear CP2k developers and users,

Have anyone encountered a problem with GFN-xTB when modeling ionic crystals? If I set

CHECK_ATOMIC_CHARGES .TRUE.

When performing CELL_OPT of a CaF_2 supercell, the program stops with the following warning:

*** WARNING in xtb_matrices.F:1088 :: Atomic charges outside chemical   ***
 *** range were detected. Switch-off CHECK_ATOMIC_CHARGES keyword in the ***
 *** &xTB section if you want to force to continue the calculation.      ***

Setting CHECK_ATOMIC_CHARGES .FALSE. makes the calculation divergent. As I get it, the charges on Ca and F become more and more unphysical in every SCF procedure, and, concomitantly, the total energy becomes lower and lower. I have attached the input and output of the divergent calculation to this message.

Could anyone give a hint on what to do in this situation? I am interested in MD of solid-liquid interfaces with ionic crystals. GFN-xTB seems the best choice.

With best regards,
Mikhail  
  -- 
 You received this message because you are subscribed to the Google Groups "cp2k" group.
 To unsubscribe from this group and stop receiving emails from it, send an email to cp... at googlegroups.com.
 To post to this group, send email to cp... at googlegroups.com.
 Visit this group at https://groups.google.com/group/cp2k.
 To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/2e624605-fb53-4994-aa7b-b5eec0d12eba%40googlegroups.com.
 For more options, visit https://groups.google.com/d/optout.
 

[attachment "test1.inp" removed by Jürg Hutter/at/UZH]
[attachment "opt.cif" removed by Jürg Hutter/at/UZH]
[attachment "opt.xyz" removed by Jürg Hutter/at/UZH]
[attachment "test1.out" removed by Jürg Hutter/at/UZH]


More information about the CP2K-user mailing list