[DFTB-Plus-User] Covergence issue

[Georgeta Ungureanu]

Dear prof. Bálint

Thank you very much for e-mail. Can you please confirm me or not if the
issue of the difference in total energies is related to the versions of
dftb+ code?
I have 2 versions of the code, and with one I get smaller difference in
energies like in 9th or 10th decimal, than with I obtained  with the one
which I used first.
Can be a numerical issue or something else?

Regards,
Georgeta



On Mon, Sep 29, 2014 at 1:43 AM, Bálint Aradi <aradi at uni-bremen.de> wrote:

> Dear Georgeta,
>
> > Can someone help me to understand why if I use exactly the same geometry
> > input file, and running the same calculation several times in different
> > directories, I get different values in total energy for a nanotube? This
> > happens on the 5th or 6th decimal.
>
> We could definitely help you much more in understanding things, if you
> had specified some more details about your calculations...
>
> Until proven being incorrect, my guess is, that it is the user behind
> the code and not the code itself making mistakes in your cases. Our
> autotest examples reuquire an accuracy of 1e-8 for most quantities
> (including energies) and we did not have any issues like the one you
> mention so far.
>
>   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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