[DFTB-Plus-User] R: R: Re: geometric optimization

Alessandro Pecchia pecchia at ing.uniroma2.it
Tue Jan 8 10:13:26 CET 2013

Dear Mahmoud,


yes it seems there is a sort of bug that escaped the testsuite. 


Please send us the ‘gen’ file. 

I assume you are using the Au set, so that ‘s not really necessary. 

But just in case you can zip the sk folder you use and send it as well.







Da: dftb-plus-user-bounces at dftb-plus.info
[mailto:dftb-plus-user-bounces at dftb-plus.info] Per conto di ahmed Mahmoud
Inviato: lunedì 7 gennaio 2013 17.45
A: dftb-plus-user at dftb-plus.info
Oggetto: Re: [DFTB-Plus-User] R: Re: geometric optimization




Thanks for answer. I also think using a field may not work in my case.
However, I have tried using normal conjugate-gradient (once indicating the
moved atoms and once without indicating them) but I got the following error:

ALLOCATION ERROR: array is already allocated


The error comes up after finishing the transport calculation ”saving the
charges”, in the first geometric step!

I attached my dftb_in file if that can help in figuring out the problem.


Thanks in advance



Date: Mon, 7 Jan 2013 16:33:59 +0100
From: pecchia at ing.uniroma2.it
To: dftb-plus-user at dftb-plus.info
Subject: [DFTB-Plus-User] R: Re: geometric optimization



You can use the normal conjugate-gradient driver. This relax all atoms
excluding contacts.


I think there are several conceptual differences between a relaxation of a
closed system in a field and an open system under bias. 


Concerning constrained charges, the dftb+negf version does not have this
feature. I will think about it. 





Inviato da Samsung Mobile 

ali sadeghi <ali.sadeqi at gmail.com> ha scritto:

Hi Ahmed, 


 Is it possible to perform geometric optimization on a device under bias?
How should the code be organized in this case?


I think you do not need the NEGB tool for this purpose. Just apply an
electric field to your system according to the desired bias. Then just relax
the geometry as usual.





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