[CP2K:4780] Semiempirical Geometry Optimization calculation with periodic boundary condition

Bharat Sharma bharats... at gmail.com
Thu Nov 7 20:07:53 CET 2013


Hello Hutter,

Thank you for your reply. I will go through your suggestions.

Bharat


On Thu, Nov 7, 2013 at 2:01 PM, <hut... at pci.uzh.ch> wrote:

> 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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