[DFTB-Plus-User] Problem with geometry convergence

[Alessandro LANDI]

Dear DFTB users,
I have followed your suggestions, but using LBFGS Minimizer, even though
the Maximal Force Component was slowly diminishing, the calculation was not
able to reach convergence, since I got the following error


ERROR!
-> Error: x need to be different in each iteration. (LBFGS Minimizer)
Note: The following floating-point exceptions are signalling:
IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO IEEE_OVERFLOW_FLAG
IEEE_UNDERFLOW_FLAG IEEE_DENORMAL

At first, I thought that something went wrong just for instance, so I tried
to restart from the last saved geometry (attached to this e-mail), but
after 4 steps I got again the abovementioned error.

I have tried to google this error, but I found nothing. Any idea about what
is going wrong?

Thank you in advance.

Best regards,
Alessandro


Il giorno lun 30 dic 2019 alle ore 13:27 Benjamin Hourahine <
benjamin.hourahine at strath.ac.uk> ha scritto:

> Hello Alessandro,
>
> it is a direct replacement for the conjugate gradient geometry driver:
>
> Driver = LBFGS {
>
> See the manual for details.
>
> Regards
>
> Ben
>
>
> 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,
> 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
>
> _______________________________________________
> DFTB-Plus-User mailing listDFTB-Plus-User at mailman.zfn.uni-bremen.dehttps://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>
> --
>         Dr.  B.  Hourahine,  Senior  lecturer
>             SUPA, Department  of  Physics,
>              University  of  Strathclyde,
>               John  Anderson  Building,
>           107 Rottenrow, Glasgow G4 0NG, UK.
>   +44 141 548 2325, benjamin.hourahine at strath.ac.uk
>
> The  Department is  a partner  in SUPA,  the Scottish
>             Universities Physics Alliance
>
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>
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-- 
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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