[QE-users] Doping

[Neelam Swarnkar]

Thanks for replying so quickly

On Thu, Jul 9, 2020, 12:10 PM Giovanni Cantele <giovanni.cantele at spin.cnr.it>
wrote:

> It is possible to simulate a doped system. However, the only way to do it
> is using a supercell approach.
>
> Indeed, doping is usually meant as a “random” distribution of
> non-interacting (or almost non-interacting)
> impurities. As such, you should choose a sufficiently large supercell (for
> example, try 2x2x2 or 3x3x3 for
> a three-dimensional cubic lattice), to prevent the impurity defects in
> neighbour supercells from interacting.
>
> Consider that if in the bulk unit cell you sample the Brillouin zone with
> a n x n x n k-point grid and study
> the impurity with an m x m x m supercell, the latter requires, to obtain
> the same accuracy with
> respect to the sampling, a n/m x n/m x n/m k-point grid (for example, if
> you use a 6x6x6 k-point grid in the
> 1x1x1 bulk unit cell, and study the impurity within a 2x2x2 supercell, for
> the latter you sample the BZ with
> a 3x3x3 k-point grid).
>
> This being said, the larger the supercell, the larger the computational
> resources (also in terms of RAM)
> you need.
>
> If you use, as you say, a “unit cell structure” (I think you mean the same
> unit cell as the bulk crystal),
> you are simulating a possibly interacting distribution of impurities, with
> concentrations usually much larger
> that the experimental ones and with defect levels that possibly exhibit
> dispersion (“defect bands”).
>
> Giovanni
>
> PS people usually do sign their posts in the forum, together with their
> affiliation.
>
> On 8 Jul 2020, at 20:32, Neelam Swarnkar <neelamswarnkar35 at gmail.com>
> wrote:
>
> Dear expert and all
>
> Doping of an atom is possible in a unit cell structure, because supercell
> taking a lot RAM for calculation.
>
> If it is possible , than please let me know.
>
> Thanks in advance
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>
> --
>
> Giovanni Cantele, PhD
>
> CNR-SPIN
> c/o Dipartimento di Fisica
> Universita' di Napoli "Federico II"
> Complesso Universitario M. S. Angelo - Ed. 6
> Via Cintia, I-80126, Napoli, Italy
>
> e-mail: giovanni.cantele at spin.cnr.it <giovanni.cantele at spin.cnr.it>
>             gcantele at gmail.com
> Phone: +39 081 676910
> Skype contact: giocan74
> Web page: https://sites.google.com/view/giovanni-cantele
>
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