[QE-developers] nonlinear core correction in phonon codes

[H. Lee]

Dear Jae-Mo Lihm:

Thank you for your reply. I will look into it.

Sincerely,

Hyungjun Lee

On Mon, Mar 30, 2020 at 6:06 AM Jae-Mo Lihm <jaemolim96 at gmail.com> wrote:

> Dear Dr. Hyungjun Lee and All,
>
> I also had the same question while working on the interpolation of phonon
> potential. And I think I found an answer, at least partially.
>
> The contribution of the nonlinear core correction is added to the variable
> dvscf in the following part of solve_linter.f90:
>         if (imode0+ipert > 0) then
>            call addcore (imode0+ipert, drhoc)
>         else
>            drhoc(:) = (0.0_DP,0.0_DP)
>         endif
>         !
>         ! Compute the response HXC potential
>         call dv_of_drho (dvscfout(1,1,ipert), .true., drhoc)
>
> So, in most parts of ph.x, multiplication of psi with dvscf gives the
> induced part *plus *the NLCC contribution, while dvqpsi_us gives the bare
> part *except *NLCC.
> In contrast, in zstar_eu, only the bare potential perturbation for atomic
> displacement is needed. Hence, the NLCC contribution is added by dvqpsi_us.
>
> I hope this answers your question.
>
> Though, I would still like to know why the ph.x code was designed this
> way.
>
> Regards,
> Jae-Mo Lihm
> Seoul National University
>
> 2020년 3월 28일 (토) 오전 12:50, H. Lee <hjunlee at gmail.com>님이 작성:
>
>> Dear Prof. Paolo Giannozzi:
>>
>> Thank you for your reply.
>>
>> Sincerely,
>>
>> Hyungjun Lee
>>
>> On Fri, Mar 27, 2020 at 3:44 AM Paolo Giannozzi <p.giannozzi at gmail.com>
>> wrote:
>>
>>> Sorry for the sloppy last sentence: "I didn't succeed".
>>>
>>> On Fri, Mar 27, 2020 at 9:42 AM Paolo Giannozzi <p.giannozzi at gmail.com>
>>> wrote:
>>>
>>>> On Thu, Mar 26, 2020 at 4:36 PM H. Lee <hjunlee at gmail.com> wrote:
>>>>
>>>>> Dear all:
>>>>>
>>>>> I have one simple and silly question on the nonlinear core correction
>>>>> in phonon codes.
>>>>>
>>>>
>>>> your question is simple but not silly at all. Some years ago I tried to
>>>> figure out where the missing core correction term was added. I didn't
>>>> manage succeed.
>>>>
>>>> Paolo
>>>>
>>>>
>>>>> The subroutine of dvqpsi_us takes care of the contribution of the
>>>>> local part of pseudopotential to dvscf.
>>>>>
>>>>> However, in most parts except for zstar_eu.f90, when calling dvqpsi_us
>>>>> the contribution due to the nonlinear core correction is not included; the
>>>>> third argument of dvqpsi_us controls the inclusion of this correction.
>>>>>
>>>>> elphon.f90:           CALL *dvqpsi_us* (ik, u (1, mode), .FALSE.,
>>>>> becp1, alphap)
>>>>>
>>>>> ep_matrix_element_wannier.f90:           CALL *dvqpsi_us* (ik, u (1,
>>>>> mode), .FALSE., becp1, alphap)
>>>>>
>>>>> raman_mat.f90:        call *dvqpsi_us* (ik, uact (1, imod),.false.,
>>>>> becp1, alphap)
>>>>>
>>>>> raman_mat.f90:           call *dvqpsi_us* (ik, uact (1,
>>>>> imod),.false., becp1, alphap )
>>>>>
>>>>> solve_linter.f90:                    call *dvqpsi_us* (ik, u (1,
>>>>> mode),.false., becp1, alphap )
>>>>>
>>>>> solve_linter.f90:                    call *dvqpsi_us* (ik, u (1,
>>>>> mode),.false., becpt, alphapt)
>>>>>
>>>>> zstar_eu.f90:           call *dvqpsi_us* (ik, u (1, mode),
>>>>> .not.okvan, becp1, alphap)
>>>>>
>>>>> Is there a specific reason to not include this correction?
>>>>> Or is this correction added in other parts of the code?
>>>>>
>>>>> Sincerely,
>>>>>
>>>>> Hyungjun Lee
>>>>> _______________________________________________
>>>>> developers mailing list
>>>>> developers at lists.quantum-espresso.org
>>>>> https://lists.quantum-espresso.org/mailman/listinfo/developers
>>>>>
>>>>
>>>>
>>>> --
>>>> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
>>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>>>> Phone +39-0432-558216, fax +39-0432-558222
>>>>
>>>>
>>>
>>> --
>>> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>>> Phone +39-0432-558216, fax +39-0432-558222
>>>
>>> _______________________________________________
>>> developers mailing list
>>> developers at lists.quantum-espresso.org
>>> https://lists.quantum-espresso.org/mailman/listinfo/developers
>>>
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