[CP2K:4771] Semiempirical Geometry Optimization calculation with periodic boundary condition

[hut... at pci.uzh.ch]

Hi

periodic NDDO calculations are not a standard application.
This type of application needs a lot of care and insight
into the implemented methods. With other words, it will not
work if you are just using defaults. 
There are many input options that need careful consideration,
especially options in the sections
&SE ... &END
&POISSON
   &EWALD
   &END
&END
Have a look in the input files in the regtest sections.
For example 
...tests/SE/regtest-3-4/Al2O3.inp

There are also some basic algorithmic problems that are associated
with the way the standard NDDO methods handle Coulomb interactions.
There is one NDDO method (PNNL) that is free from this problem,
unfortunately, there is no real parameter list available. 

To make this clear again. It only makes sense to try to use this
options if you are willing to dig deep into the theory and algorithms
of these simulation methods. 

regards

Juerg

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich               E-mail:  hut... at pci.uzh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: bharat 
Sent by: cp... at googlegroups.com
Date: 11/06/2013 05:13PM
Subject: [CP2K:4771] Semiempirical Geometry Optimization calculation with periodic boundary condition

Hello Everyone,

I am trying to perform geometry optimization calculation using semiempirical methods AM1, PM3, RM1, and PM6 with periodic boundary condition for bulk water. It is found that SCF is not converged and the structures are very bad. (O-H bond lengths increased to 5-8 A and structure is not converged.) 

Does anyone have experience using semiempirical methods for PBC calculation?

All suggestions are appreciated. 

Thank you.

Bharat Sharma

  
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