[DFTB-Plus-User] Problem with geometry convergence

Benjamin Hourahine benjamin.hourahine at strath.ac.uk
Mon Dec 30 13:27:13 CET 2019

Hello Alessandro,

it is a direct replacement for the conjugate gradient geometry driver:

Driver = LBFGS {

See the manual for details.



On 20/12/2019 15:33, Alessandro LANDI wrote:
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,

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


Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen

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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