[QE-users] lda_plus_u_kind=2

[Andrew Supka]

Thanks to both of you for the response!

On Mon, Jul 20, 2020, 03:59 Timrov Iurii <iurii.timrov at epfl.ch> wrote:

> Dear Andrew,
>
>
> > From looking into the code a bit it appears to me that it generates a
> 3x3x3 supercell with (I am guessing) ±R in each direction of the lattice
> vectors.
>
>
> Right
>
>
> > I see that for the orginal unit cell the indices go 1-nat
>
>
> Right
>
>
> > ...but I am unsure on how the indices in the adjacent unit cells are
> chosen.
>
>
> See the routine q-e/PW/src/intersite_V.f90, lines 88-113.
>
>
> When sc_size=1 you have a supercell 3x3x3, when sc_size=2 you have 5x5x5,
> etc. In most cases 3x3x3 is enough.
>
>
> > I would like to specify a hubbard V between atom1 at the edge of the
> unit cell R=[0,0,0] and a nearest neighbor, atom2, in an adjacent unit cell
> R=[0,0,1].
>
>
> It can be quite painful to do all this "by hand". I suggest to use the HP
> code, and you will get all possible pairs of neighbors automatically, and
> then you choose what you want. We will try to prepare some tutorial about
> DFT+U+V in the near future.
>
>
> 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
> Andrew Supka <supkaand at gmail.com>
> *Sent:* Sunday, July 19, 2020 1:27:09 AM
> *To:* Quantum ESPRESSO users Forum
> *Subject:* Re: [QE-users] lda_plus_u_kind=2
>
> Thank you for the response. From looking into the code a bit it appears to
> me that it generates a 3x3x3 supercell with (I am guessing) ±R in each
> direction of the lattice vectors. I see that for the orginal unit cell the
> indices go 1-nat but I am unsure on how the indices in the adjacent unit
> cells are chosen.
>
> Is there a part of that code that you'd suggest I check for information on
> that?
>
> Andrew Supka
> Postdoc Physics
> Central Michigan University
>
>
> On Sat, Jul 18, 2020, 16:54 Matteo Cococcioni <matteo.cococcioni at unipv.it>
> wrote:
>
>> This part of the code is still not so user-friendly (in fact still under
>> improvement).
>> yes the code recognizes all the neighbors at the same distance and puts
>> the same V between them. You just need to find one of them in the unit cell
>> and make sure that that atom (or one of its periodic replicas) belongs to
>> the proper star of neighbors you are treating with V.
>> In order to do that it might be a good idea to shift the reference atom
>> to the center of the cell, so you increase the chances to find one of its
>> neighbors in the unit cell.
>>
>> HTH
>>
>> Matteo
>>
>> Il giorno sab 18 lug 2020 alle ore 17:38 Andrew Supka <supkaand at gmail.com>
>> ha scritto:
>>
>>> I have been experimenting with the developers version cloned from
>>> gitlab. I would like to specify a hubbard V between atom1 at the edge of
>>> the unit cell R=[0,0,0] and a nearest neighbor, atom2, in an adjacent unit
>>> cell R=[0,0,1]. It appears that the code automatically finds the equivalent
>>> atoms to the site you put a hubbard U and applies the V to those also.
>>>
>>> I have attempted to put the V on the equivalent to atom2 in R=[0,0,0]
>>> but it assumes I want the V between the two atoms in R=[0,0,0].
>>>
>>> I have also tried adding the V using an index corresponding to another
>>> unit cell. I'm not sure how the indices for the atoms are chosen when the
>>> algorithm finds equivalent sites.
>>>
>>> Is there a simple way to do what I detailed above? Also if I'm way off
>>> please let me know.
>>>
>>> Thank you for any information you can provide.
>>>
>>> Andrew Supka
>>> Postdoc Physics
>>> Central Michigan University
>>> _______________________________________________
>>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso
>>> )
>>> users mailing list users at lists.quantum-espresso.org
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>>
>>
>>
>> --
>> Matteo Cococcioni
>> Department of Physics
>> University of Pavia
>> Via Bassi 6, I-27100 Pavia, Italy
>> tel +39-0382-987485
>> e-mail matteo.cococcioni at unipv.it <lucio.andreani at unipv.it>
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
>> users mailing list users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
>
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