[DFTB-Plus-User] Applying an electric field with periodic boundaries

[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.


>
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> 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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