[DFTB-Plus-User] Further inquiry on the geometry optimization

[Bálint Aradi]

Dear Iresh,

>  I went through as you instructed but , I could not figure out how to
> fix the bond distance because it is a transition of open to close
> .Constrain{} function and the move atom{}  do not have any option to fix
> the bond length during the ring opening and the closing .

I still do not know, what you plan to do, so hard to give any advice.
You can not relax structures or make MD in DFTB+ with constrained bond
lengths as we do not have SHAKE or RATTLE implemented. In some cases,
for example if you calculate some property as function of the bond
length, however, it could be enough to fix the two atoms making up the
bonds and relax everything else. If latter works for you, you can do it
easily with DFTB+. If not, you won't be able to do it right now.

  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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