[DFTB-Plus-User] DFTB-Plus-User Digest, Vol 32, Issue 3

[Ashwin Ramasubramaniam]

Hello Ben,

Thanks for your reply. I have a sheet of graphene which is periodic in x and
y (and a large periodic distance in z) and I want to apply a uniform field
across it in the z direction. The example in the autotest directory is not
particularly clear to me. At any rate, is the idea that I model the electric
field by inserting sheets of positive and negative charges (so that I
basically have a parallel plate capacitor with graphene between the plates)?

thanks,
-Ashwin.


On Wed, Aug 4, 2010 at 6:00 AM, <dftb-plus-user-request at dftb-plus.info>wrote:

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>   1. Re: Applying an electric field with periodic      boundaries
>      (Ben Hourahine)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 04 Aug 2010 10:05:44 +0100
> From: Ben Hourahine <benjamin.hourahine at strath.ac.uk>
> Subject: Re: [DFTB-Plus-User] Applying an electric field with periodic
>        boundaries
> To: User list for DFTB+ related questions
>        <dftb-plus-user at dftb-plus.info>
> Message-ID: <4C592D68.7000904 at strath.ac.uk>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hello Ashwin,
>
> what type of electric field do you need to apply? Currently the code
> can only include point charges when using periodic boundary conditions.
> The syntax is described in the  ElectricField section in the dftb+ v1.1
> manual, and there is an example in the autotest directory at:
> scc/H2O-extchrg-periodic
>
> This is not equivalent to the recent methods to calculate properties
> with constant values of E, D or P based on the modern theory of
> polarization.
>
> Regards
>
> Ben
>
> Ashwin Ramasubramaniam wrote:
> > Hello DFTB+ users,
> >
> > I see from the manual that an external field can only be applied for
> > non-periodic systems. Presumably a periodic system requires the use of
> > point charges. Is there an example available (or would any of the users
> > be kind enough to share one) for how to go about applying an external
> > field using point charges in the periodic case?
> >
> > thanks,
> > -Ashwin.
> >
>
> --
>     Dr. B. Hourahine, 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 University of Strathclyde is a charitable body,
> registered in Scotland, with registration number SC015263
>
>
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> End of DFTB-Plus-User Digest, Vol 32, Issue 3
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