[DFTB-Plus-User] Problem with geometry convergence

[Alessandro LANDI]

Dear Bálint,
thank you very much for your answer. However, I do not fully understand
where you modified the input: in the attached dftb_in.hsd you sent me I
still see "Driver = ConjugateGradient", and the only two differences I see
are "MixingParameter = 0.2" and "MaxForceComponent = 1.E-4". Where did you
set the LBFGS optimizer? Am I missing something?

Best regards,
Alessandro

Il giorno ven 20 dic 2019 alle ore 16:26 Bálint Aradi <aradi at uni-bremen.de>
ha scritto:

> Dear Alessandro,
>
> The total energy landscape of your molecule is rather flat, our CG
> driver has usually difficulties with such scenarious. Using the LBFGS
> optimizer as shown in the attached dftb_in.hsd file, I was able to
> converge your geometry up to a tolerance of 1e-4 with DFTB+ 19.1.
>
> I left the D3-dispersion as it was, but please note, that the default
> damping parameters (as you did not set those explicitely) require DFTB3
> (3rd order and XH-damping) and the 3ob SK-set! They are not considered
> in the attached example as I wanted to introduce as few changes as
> possible. Nevertheless, make sure you change it accordingly for any
> serious production calculations.
>
>   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/
>
>

-- 
Alessandro Landi, Assegnista di Ricerca
Dipartimento di Chimica e Biologia "Adolfo Zambelli"
Università degli Studi di Salerno
Via Giovanni Paolo II, 132 - 84084 - Fisciano (SA)
Phone number 089969390
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