[CP2K:7074] PM6 convergence with periodic boundary conditions

[hut... at chem.uzh.ch]

Hi

just to be sure. You need to have atoms and cell doubled.
If you only double the cell you end up with a cluster in 
a large box.

    &TOPOLOGY
      MULTIPLE_UNIT_CELL ${NREP} ${NREP} ${NREP}
    &END
    &CELL
      ABC a b c
      MULTIPLE_UNIT_CELL ${NREP} ${NREP} ${NREP}
    &END CELL

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: Jack Evans 
Sent by: cp... at googlegroups.com
Date: 10/21/2015 02:34PM
Subject: Re: [CP2K:7074] PM6 convergence with periodic boundary conditions

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

Winterthurerstrasse 190

CH-8057 Zürich, Switzerland

---------------------------------------------------------------



-----cp... at googlegroups.com wrote: -----To: cp2k <cp... at googlegroups.com>

From: Jack Evans 

Sent by: cp... at googlegroups.com

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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