[Pw_forum] KZK method

[Luke Shulenburger]

My understanding is that the correction should apply regardless of the
stress on the structure.  Certainly the correction would not be right
if the KZK structure was different from the one used for QMC and LDA.
At the end of the day though, the only way to be 100% sure this is
working correctly is to try a couple of supercell sizes and see two
things.  The first is that the corrected energy agrees for larger
supercell sizes and the second is that extrapolations of the
uncorrected energy to the infinite supercell limit agree with the
finite size corrected result.  Figure 3 of the original KZK paper
(Phys. Rev. Lett. 100, 126404 (2008)) should illustrate how this works
for Si.  You might also want to compare the results to those obtained
using the MPC+Chiesa correction (Phys. Rev. Lett. 97, 076404 (2006))
if your QMC code supports it.

Luke
Geophysical Laboratory
Carnegie Institution of Washington

On Thu, Jun 10, 2010 at 2:27 PM, mohaddeseh abbasnejad
<m.abbasnejad at gmail.com> wrote:
> Dear Luke,
>
> Thanks for your reply.
> I meant that if I want to calculate the LDA energy with a L*L*L mesh using
> KZK functional
> ( for correction of QMC L*L*L supercell calculation):
>  E=Edmc(L*L*L)+Elda-converged-Elda-kzk(L*L*L)
> Do i have to relax structure, because for example the stresses on the
> structure with KZK correction and L*L*L mesh are not small at all?
> Thanks in advance.
>
> Yours,
> Mohaddeseh
>
>
> On Thu, Jun 10, 2010 at 9:14 PM, Luke Shulenburger <lshulenburger at gmail.com>
> wrote:
>>
>> Are you meaning that you would like to use a nonuniform mesh of
>> kpoints to generate a supercell from your DFT calculation?  If so, I
>> have some code that I have been using that computes the volume for KZK
>> from cell volume * number of k_points enumerated.
>>
>> Luke Shulenburger
>> Geophysical Laboratory
>> Carnegie Institution of Washignton
>>
>> On Thu, Jun 10, 2010 at 3:39 AM, mohaddeseh abbasnejad
>> <m.abbasnejad at gmail.com> wrote:
>> >
>> > Dear all,
>> >
>> > In order to perform KZK correction, I wonder if it is needed to relax
>> > the
>> > L*L*L structure?
>> >
>> > Thanks in advance.
>> >
>> > Yours,
>> > Mohaddeseh
>> >
>> >
>> >
>> > On Mon, Jun 7, 2010 at 7:51 PM, William Parker
>> > <wparker at mps.ohio-state.edu>
>> > wrote:
>> >>
>> >> Hi Mohaddeseh,
>> >>
>> >> KZK is in QE.  Just use input_dft='kzk', and QE will use the volume of
>> >> your cell to calculate the finite-size correction.  Compare that to the
>> >> value using PZ-LDA to get your correction for QMC.
>> >>
>> >> --William
>> >>
>> >> ======================================================================
>> >> William Parker              Tel :  +1 (614) 292-2887
>> >> Graduate Research Associate Fax :  +1 (614) 292-7557
>> >> Ohio State University
>> >> Department of Physics
>> >> 191 West Woodruff Avenue    email: wparker at mps.ohio-state.edu
>> >> Columbus, OH  43210-1117    http://www.physics.ohio-state.edu/~wparker
>> >> U.S.A.
>> >>
>> >> Office: 2025 Physics Research Building
>> >> ======================================================================
>> >>
>> >> On Mon, 7 Jun 2010, mohaddeseh abbasnejad wrote:
>> >>
>> >> > Dear all,
>> >> >
>> >> > Would you please let me know if KZK method (Kwee, Zhang, and
>> >> > Krakauer)
>> >> > has
>> >> > been implemented in PWscf code? If so, how should I use it?
>> >> > Thanks in advance.
>> >> >
>> >> > Yours,
>> >> > ---------------------------------------------------------
>> >> >
>> >> > Mohaddeseh Abbasnejad,
>> >> > Room No. 323, Department of Physics,
>> >> > University of Tehran, North Karegar Ave.,
>> >> > Tehran, P.O. Box: 14395-547- IRAN
>> >> > Tel. No.: +98 21 6111 8634  & Fax No.: +98 21 8800 4781
>> >> > Cellphone: +989177317514
>> >> > E-Mail:     m.abbasnejad at gmail.com
>> >> > Website:  http://physics.ut.ac.ir
>> >> >
>> >> > ---------------------------------------------------------
>> >> >
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>> >
>> >
>> > --
>> > ---------------------------------------------------------
>> >
>> > Mohaddeseh Abbasnejad,
>> > Room No. 323, Department of Physics,
>> > University of Tehran, North Karegar Ave.,
>> > Tehran, P.O. Box: 14395-547- IRAN
>> > Tel. No.: +98 21 6111 8634  & Fax No.: +98 21 8800 4781
>> > Cellphone: +989177317514
>> > E-Mail:     m.abbasnejad at gmail.com
>> > Website:  http://physics.ut.ac.ir
>> >
>> > ---------------------------------------------------------
>> >
>> >
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>
>
> --
> ---------------------------------------------------------
>
> Mohaddeseh Abbasnejad,
> Room No. 323, Department of Physics,
> University of Tehran, North Karegar Ave.,
> Tehran, P.O. Box: 14395-547- IRAN
> Tel. No.: +98 21 6111 8634  & Fax No.: +98 21 8800 4781
> Cellphone: +989177317514
> E-Mail:     m.abbasnejad at gmail.com
> Website:  http://physics.ut.ac.ir
>
> ---------------------------------------------------------
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