[CP2K:7068] PM6 convergence with periodic boundary conditions

[Jack Evans]

Dear Juerg,

Thank you for the prompt answer.

The system does converge with the modification of including a 2x2x2 
supercell. Below, for other users, is the modification made to the 
SE/regtest-3-4/Al2O3.inp.

&CELL

      ABC [angstrom] 4.75900    4.75900   12.99100

      ALPHA_BETA_GAMMA [deg]  90.00000   90.00000  120.00000

      MULTIPLE_UNIT_CELL 2 2 2

&END


Cheers,


Jack

On Wednesday, October 21, 2015 at 8:59:59 AM UTC+2, jgh wrote:
>
> Hi 
>
> the periodic NDDO code has not been used often. It is not very well tested 
> and we lack experience on how to use it efficiently. 
> Nevertheless, I managed to converge the Al2O3 system using a 2x2x2 cell 
> and CG minimizer with line search. It took a few hundred steps. 
> The problem is that the different cutoffs for Coulomb and Exchange have 
> to make sense numerically and physically. 
>
> 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 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: -----To: cp2k <
> cp... at googlegroups.com <javascript:>> 
> From: Jack Evans 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 10/19/2015 02:50PM 
> Subject: [CP2K:7068] PM6 convergence with periodic boundary conditions 
>
> Dear team, 
> I have been investigating the application of PM6 within the CP2K program 
> for the study of periodic structures. 
> Currently, I understand that periodic NDDO calculations are not a standard 
> application and thus require care and to begin I have been testing the 
> convergence of structures defined in the regtest section.  
> In particular, I have noticed the simulation of Al2O3 
> (SE/regtest-3-4/Al2O3.inp) does not converge despite increasing the number 
> of SCF cycles to 2000 and using a variety of optimiser settings. 
> I have been testing this with cp2k/2.4.0 and cp2k/2.6.2 complied with 
> intel compilers. 
>
>
>
>
>
>
>
>
> Thank you for your help in advance. 
> Cheers, 
> Jack 
>
>
>
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