[Pw_forum] vdW functional not implemented for spin polarized runs

[Duy Le]

On Fri, Apr 29, 2011 at 3:49 AM, Stefano de Gironcoli <degironc at sissa.it> wrote:
> Dear all,
>
>     I inquired Timo Thonhauser (now Wake Forest  University), the main
> character behind the vdW-DF functional implementation in Quantum
> ESPRESSO,  about the issue of the spin-polarized version of vdW-DF.
>
> I'm reporting his opinion below:
>
> "In general, at the moment there exists NO true extension of vdW-DF for
> spin-polarized cases. Several groups have expressed interest in working
> on it, but nothing has been published yet. Note that just evaluating
> vdW-DF for the two spin densities separately, while simple to implement,
> is an approximation which is difficult to justify: there is no
> quantitative measure of the error being made, other than hand waving
> arguments that it has to be small. Also, we did not implement that
> simple fix, because we were afraid that people would use it as a
> black-box for spin-polarized calculations, not knowing that there is no
> spin-polarized vdW-DF"
>
> hope this helps to clarify the situation.
>
> stefano

Thank you Stefano and Thonhauser Timo for the clarification.

--------------------------------------------------
Duy Le
PhD Student
Department of Physics
University of Central Florida.

"Men don't need hand to do things"

>
>
>
> On 04/27/2011 04:45 PM, Duy Le wrote:
>> --------------------------------------------------
>> Duy Le
>> PhD Student
>> Department of Physics
>> University of Central Florida.
>>
>> "Men don't need hand to do things"
>>
>>
>>
>> On Wed, Apr 27, 2011 at 3:29 AM, Stefano de Gironcoli<degironc at sissa.it>  wrote:
>>> the vdW energy depends on the local polarizability of the electron gas ..
>>> does it depend on the spin density ? I would say so.
>> I would depend as we expected, however, from the formalism of vdW-DF,
>> spin is not taken into account. So, I think in the limit of vdW-DF,
>> the spin-dependence is ignored.
>>
>>> Is it taken into account in the current definition of vdw-DF ? I would say
>>> no...
>>> how is it implemented in GPAW ? just blindly or with some argument ?
>> I am not sure. Did not have a chance to look at it and there is no
>> found document about this.
>>
>>> stefano
>>>
>>> On 04/27/2011 06:35 AM, WANG Wei wrote:
>>>
>>> Thank you for your advice, Deu. Yes, the non-local energy is independent the
>>> spin density.
>>>
>>>
>>> On 27 April 2011 12:34, Duy Le<ttduyle at gmail.com>  wrote:
>>>
>>> --------------------------------------------------
>>> Duy Le
>>> PhD Student
>>> Department of Physics
>>> University of Central Florida.
>>>
>>> "Men don't need hand to do things"
>>>
>>>
>>>
>>> On Tue, Apr 26, 2011 at 1:00 PM, Stefano de Gironcoli<degironc at sissa.it>
>>> wrote:
>>>
>>> Dear  WANG Wei
>>>    the vdw-DF functional form is not defined for spin polarized system...
>>>
>>> Or it does mean that non-local energy is not spin-dependent but
>>> charge-density-dependent only.
>>>
>>>    if you define, implement and test it, you could even get a nice
>>> publication out of it. thank you.
>>>
>>> The spin-polarized vdW-DF has been implemented in GPAW.
>>>
>>> stefano
>>>
>>>
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>>
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>>
>>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>