[Pw_forum] Applying sawtooth filed parallel to a system

[Thomas Brumme]

Dear Ghadiyali Mohammed Kader,

the paper by Meyer and Vanderbilt is fine - no use to read the one by 
Bengtsson.
In general, you can apply an electric field using the sawtooth potential 
in every
system with at least one non-periodic direction. Note that you need to 
place the
potential jump (i.e., the dipole which is used to model the electric 
field) in the
vacuum region, and the field along a non-periodic direction...
In the case of your nanoribbon this would be the x- and y-direction. 
Usually, you
also need to switch on the dipole correction (dipfield = .true.).

Regards

Thomas

On 08.01.2018 11:49, Mohammed Ghadiyali wrote:
>
> Respected Sir,
>
>
> Thanks for the information.
>
>
> Actually, I had checked this paper: Meyer and Vanderbilt, PRB 63, 
> 205426 (2001)
>
> And was not able to find any details regarding the parallel field, I 
> would read the other paper as well, thanks for the reference.
>
>
> I do have an additional question, is it possible to apply an electric 
> field to a nanoribbon, like a graphene nanoribbon, which has vacuum on 
> two axis, I have attached an input.
>
>
>
> Regards,
>
> Ghadiyali Mohammed Kader.
>
> Research Scholar,
> Dept. of Physics,
> University of Mumbai.
>
> ------------------------------------------------------------------------
> *From:* Thomas Brumme <thomas.brumme at uni-leipzig.de>
> *Sent:* Monday, January 8, 2018 4:00 PM
> *To:* Mohammed Ghadiyali; PWSCF Forum
> *Subject:* Re: [Pw_forum] Applying sawtooth filed parallel to a system
> Dear Ghadiyali Mohammed Kader,
>
> there was no input file attached to your mail. Anyway... The electric 
> field via "tefield"
> can only be used in systems where you have a vacuum region in which 
> you can place
> the potential jump. Maybe you should have a look at, e.g.,
>
> L. Bengtsson, Phys. Rev. B 59, 12301 (1999)
>
> to understand what this method is about. If you want to apply an 
> electric field via the
> modern theory of the polarization have a look at the input variable 
> "lelfield" and
> example 4 of PW.
>
> Regards
>
> Thomas
>
> On 08.01.2018 11:17, Mohammed Ghadiyali wrote:
>>
>> Respected Sir,
>>
>>
>> Thanks for the input.
>>
>>
>> But, if one is dealing with a bulk system with no vacuum then the 
>> potential jump would be in the system?
>>
>>
>> Regards,
>> Ghadiyali Mohammed Kader,
>> Research Scholar,
>> Dept. of Physics,
>> University of Mumbai.
>>
>> ------------------------------------------------------------------------
>> *From:* Thomas Brumme <thomas.brumme at uni-leipzig.de> 
>> <mailto:thomas.brumme at uni-leipzig.de>
>> *Sent:* Monday, January 8, 2018 3:33 PM
>> *To:* PWSCF Forum; Mohammed Ghadiyali
>> *Subject:* Re: [Pw_forum] Applying sawtooth filed parallel to a system
>> Dear Ghadiyali Mohammed Kader,
>>
>> applying the electric field parallel to the system, thus placing the 
>> potential jump "into" the system
>> makes no sense and is wrong. Yet, if you provide more details on what 
>> you actually want to do,
>> someone might be able to help.
>>
>> Regards
>>
>> Thomas
>>
>> On 08.01.2018 08:05, Mohammed Ghadiyali wrote:
>>>
>>> Dear All,
>>>
>>>
>>> Is it possible to use the sawtooth method as I require smearing for 
>>> applying electric field parallel to a system?
>>>
>>>
>>> I do understand the parameter edir can be used to specify the 
>>> direction, but it also specifies the direction of vacuum.
>>>
>>> I mean, I have a vacuum along the z-direction and I want to apply 
>>> the electric field along the x and y-direction.
>>>
>>> Then how to select the values of emoxpos and eopreg?
>>>
>>>
>>> Regards,
>>>
>>> Ghadiyali Mohammed Kader,
>>>
>>> Research Scholar,
>>>
>>> Dept. of Physics,
>>>
>>> University of Mumbai.
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
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>>
>> -- 
>> Dr. rer. nat. Thomas Brumme
>> Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
>> Leipzig University
>> Phillipp-Rosenthal-Strasse 31
>> 04103 Leipzig
>>
>> Tel:  +49 (0)341 97 36456
>>
>> email:thomas.brumme at uni-leipzig.de <mailto:thomas.brumme at uni-leipzig.de>
>
> -- 
> Dr. rer. nat. Thomas Brumme
> Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
> Leipzig University
> Phillipp-Rosenthal-Strasse 31
> 04103 Leipzig
>
> Tel:  +49 (0)341 97 36456
>
> email:thomas.brumme at uni-leipzig.de <mailto:thomas.brumme at uni-leipzig.de>

-- 
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig

Tel:  +49 (0)341 97 36456

email: thomas.brumme at uni-leipzig.de

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