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

[mpol]

Dear Juerg,

Thanks for the reply. Notably, I had no such problem with small clusters 
and molecules.

Unfortunately, I have to pass on the idea to use GFN-xTB for now, in this 
case.

With best regards,
Mikhail

четверг, 4 июля 2019 г., 19:01:42 UTC+3 пользователь jgh написал:
>
> 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: 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: "mpol" 
> Sent by: c... at googlegroups.com <javascript:> 
> 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   
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> [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] 
>
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