[DFTB-Plus-User] Geometry and Lattice Optimisation Problems

Bálint Aradi balint.aradi at bccms.uni-bremen.de
Mon May 26 10:24:39 CEST 2014


Dear Andrew,

On 05/26/2014 08:30 AM, Andrew Tarzia wrote:
> Hi, 
> 
> I have been trying to optimise a literature Covalent Organic Framework
> structure with both the matsci-0-3 (recommended by DFTB.org) and the
> mio-0-1 (recommended by another researcher in this field who has
> successfully used it before). All test structures from papers
> successfully optimised in no time.
> 
> With both skf packs I have had trouble optimising structures with
> Nitrogens present. The matsci pack works fine for COBH.
> 
> The problem is the structure of aromatic sections that become deformed
> (and non planar).
> 
> Has anyone experienced this? Is it an issue with my simulation or the
> skf files?

I can't comment on COFs, as I have never worked with them. However, I
know that nitrogen definitely belongs to the non-trivial elements. In
some of the sets, even extra repulsives are created for specific
N-related cases (e.g. miomod:nh, 3ob:nh). So, it could be, that also in
your case, the N-parametrization is not good enough for your system.

  Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/


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