[DFTB-Plus-User] Dispersion correction in DFTB+NEGF

[Gabriele Penazzi]

On 06/08/2014 03:25 PM, anz118466 at cse.iitd.ac.in wrote:
> Dear all,
>
> I had a small query regarding the DFTB+NEGF package. Is dispersion
> correction supported for the same? The DFTB+NEGF manual mentions about the
> use of SlaterKirkwood model. Can I include this in my transport
> calculations for considering van der waals forces?

Dear Anusha,

we are generally trying to keep all the usual DFTB+ features in the
transport trunk, therefore we did not specifically remove anything for
dispersion correction but neither we tested a case like you mention.

The reason is that van der Waals forces are long electrostatic forces
and they do not enter directly the electronic Hamiltonian, therefore
they do not affect charge transport. One case I could imagine would be
if you want to calculate forces out of equilibrium and include also
dispersion correction, but such a feature is not supported yet.

Going back to the allocation error, which should not be there in any
case, can you give us some more information?
How large is the system? Did you try a small test case? Does the normal
transport calculation without SlaterKirkwood correction work properly?

Best,
Gabriele


>
> Also, when I incorporated the dispersion block in my dftb+negf simulation,
> I encountered the following error:
>
> ALLOCATION ERROR
>
> Is this due to some memory shortage?
>
> Thanks & Regards,
> Anusha Iyer
>
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-- 
Dr. Gabriele Penazzi
BCCMS - University of Bremen

http://www.bccms.uni-bremen.de/
http://sites.google.com/site/gabrielepenazzi/

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