[Pw_forum] If one atom is heavy, another is lighter, what type of pseudo potentials should be used ?

[Sitangshu Bhattacharya]

Dear Eduardo,

You are right. Thumb rule is: there is no appreciable splittings in the
band edges with atoms with at. number < 40. However, if the crystal is
having time reversal symmetry and your are working with multiple layers, I
would suggest to take fully relativistic, nc, core-corrected pseudo for all
the species. In this way you can get the spin occupancy in different |n,k>
due to different atoms. This kind of approach will give you much detailed
information when you calculate the 1st and second order electron-phonon
self energies/GW/BSE, etc.

Regards,
Sitangshu


On Mon, Jan 8, 2018 at 1:57 AM, Eduardo Menendez <eariel99 at gmail.com> wrote:

> Dear Sitangshu,
>
> Could you, please, expand your answer? I used to think that the spin-orbit
> coupled pseudopotential is no needed for the light atom.
> I just think that the spin components are in the wave function as long as
> one set noncollinear=.true. , or, alternatively, that the coupling terms in
> the psp of light atoms should be very small.
>
> Is there any article explaing the theory of spin-orbit coupled
> pseudopotential calculations and/or pseudopotential generation?
>
> Best regards,
> Eduardo Menendez Proupin
> University of Chile
>
> ---------- Mensaje reenviado ----------
> From: Sitangshu Bhattacharya <sitangshu at iiita.ac.in>
> To: PWSCF Forum <pw_forum at pwscf.org>
> Cc:
> Bcc:
> Date: Sat, 6 Jan 2018 22:47:40 +0530
> Subject: Re: [Pw_forum] If one atom is heavy, another is lighter, what
> type of pseudo potentials should be used ?
> Dear Jagadish,
>
> It depends what you are trying to achieve. For example, spins are required
> for all elements if your target is to compute optical processes... etc.
>
> Regards
> Sitangshu
>
>
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-- 
**********************************************
Sitangshu Bhattacharya (সিতাংশু ভট্টাচার্য), Ph.D
Assistant Professor,
Room No. 2221, CC-1,
Nanoscale Electro-Thermal Laboratory,
Department of Electrical and Communication Engineering,
Indian Institute of Information Technology-Allahabad
Uttar Pradesh 211 012
India
Telephone: 91-532-2922000 Extn.: 2131
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/
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