[QE-users] Momentum matrix element on PBE+U

[L Y]

Dear Lurii,

Thank you for the quick response!
Did you mean [J. Chem. Phys. 120, 9935 (2004)] by Toby and Dal Corso? I
could not find an expression for the momentum matrix element in that
reference, I think that reference is only about the extra term involving
the ultrasoft pseudopotential?
I ask because I have calculated the momentum matrix elements between
valence and conduction bands along symmetry lines in MgO. Everything seems
OK, except the fact that there is a noticeable discontinuity of the matrix
element at the Gamma point. I did extensive debugging, but could find
anything wrong (the band energies are fine and continuous without
discontinuity). I suspect I need to do something special for the momentum
matrix element, but I cannot figure out the expression.

Best regards,
Lun Yue
Louisiana State University

Den tor. 14. maj 2020 kl. 11.55 skrev Timrov Iurii <iurii.timrov at epfl.ch>:

> Dear Lun Yue,
>
>
> The reference is written in the header of that routine.
>
>
> Greetings,
>
> Iurii
>
>
> --
> Dr. Iurii Timrov
> Postdoctoral Researcher
> STI - IMX - THEOS and NCCR - MARVEL
> Swiss Federal Institute of Technology Lausanne (EPFL)
> CH-1015 Lausanne, Switzerland
> +41 21 69 34 881
> http://people.epfl.ch/265334
> ------------------------------
> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of lot
> fun <xifntx at gmail.com>
> *Sent:* Thursday, May 14, 2020 6:45:16 PM
> *To:* Quantum ESPRESSO users Forum
> *Subject:* Re: [QE-users] Momentum matrix element on PBE+U
>
> Dear Lurii,
>
> I was wondering whether you have any reference on how the momentum matrix
> element is implemented in QE?
> Obviously the PP/src/compute_ppsi.f90 routine is crucial, but I dunno
> which formula is used there. A reference to a paper would be
> greatly appreciated!
>
> Best regards,
> Lun Yue
> Louisiana State University
>
> Den ons. 13. maj 2020 kl. 03.06 skrev Timrov Iurii <iurii.timrov at epfl.ch>:
>
>> > I encounter this error: 'Error in routine write_p_avg (1): write_p_avg
>> not working with LDA+U'.
>>
>>
>> The LDA+U does not work in this case because there is a missing term, see
>> Eq. (53) in PRB 101, 064305 (2020).
>>
>>
>> > Is there a way to circumvent this on Quantum Espresso?
>>
>>
>> I do not know any apart from adding the missing term.
>>
>>
>> Iurii
>>
>>
>> --
>> Dr. Iurii Timrov
>> Postdoctoral Researcher
>> STI - IMX - THEOS and NCCR - MARVEL
>> Swiss Federal Institute of Technology Lausanne (EPFL)
>> CH-1015 Lausanne, Switzerland
>> +41 21 69 34 881
>> http://people.epfl.ch/265334
>> ------------------------------
>> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of
>> Shivesh Sivakumar <shiveshsivakumar at gmail.com>
>> *Sent:* Wednesday, May 13, 2020 8:14:25 AM
>> *To:* Quantum ESPRESSO users Forum
>> *Subject:* [QE-users] Momentum matrix element on PBE+U
>>
>> Hello users,
>>
>> Sorry for the repost, but I think my question went unnoticed.
>> Is there a way to calculate the momentum matrix element in PBE+U on QE? I
>> encounter this error: 'Error in routine write_p_avg (1): write_p_avg not
>> working with LDA+U'. Is there a way to circumvent this on Quantum Espresso?
>>
>> Best,
>> Shivesh Sivakumar
>> University of Washington
>> Seattle-WA, 98105
>>
>>
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