[QE-users] Requesting Help With Spin Orbit Coupling Spin-Separated Bands Extraction

[Manocha, Pratyush]

Dear Professor Luiz,

I apologize for my delayed response; I had exams to appear for.

Thank you for informing me about the "lsigma" keyword. While it doesn't solve my problem of segregating spin-up bands from spin-down ones, it gives me the expectation values of the total angular momentum along the x, y, and z axes, right?

I tried extracting the data for GaAs, and I noticed from the results that often, the expectation values are values other than 0.5, 0, and -0.5; does this mean that, at these points, the band has a mix of both spin-up and spin-down electrons?

Another question I had is: when you say that I can color the bands according to the spin values like a fatband plot, do you mean that each band would individually be coloured from "colour a" to "colour b" based on the spin values at the different k points along the chosen "k-path?"

Thank you very much for helping me with this!

Regards,
Pratyush Manocha
Graduate Student | M.S. Electrical & Computer Engineering
School of Electrical and Computer Engineering
Georgia Institute of Technology
________________________________
From: Luiz Gustavo Davanse da Silveira <lgsilveira at fisica.ufpr.br>
Sent: Thursday, February 16, 2023 14:03
To: Manocha, Pratyush <pmanocha at gatech.edu>
Cc: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Requesting Help With Spin Orbit Coupling Spin-Separated Bands Extraction

Dear Pratyush Manocha,

I believe the spin_component variable doesn't work with noncollinear
calculations. You can however use the lsigma variable in bands.x input to
get the spin components at each k-point for every band. Then, for
instance, you can use this information to color the band plot according to
spin values (like a fatbands plot).

Best Regards,

Luiz Gustavo Silveira
Assistant professor, Department of Physics - Federal University of Paraná
Curitiba - Brazil

Em Seg, Dezembro 19, 2022 7:22 pm, Manocha, Pratyush escreveu:
> Dear All,
>
>
> I am using QE-7.1 and want to plot the spin-orbit coupled bands for
> Silicon and later on, GaN. I ran a few simulations for Silicon (with a
> fully relativistic pseudopotential obtained from PSLibrary 1.0.0) by
> turning on the "lspinorb" and "noncolin" keywords and specifying a
> non-zero "starting_magnetization" in the "&system" namecard.  The
> simulation runs smoothly, however, when I try to extract the bands for
> just spin-down electrons using "spin_component=2" in the input file given
> to the bands.x code, it returns the following error: Error in routine
> punch_bands (1):      incorrect spin_component???.
>
> I went through the archive and also tried simulating with various
> different keyword combinations using "nspin" and "lspinorb", and I found
> that "lspinorb" requires non-colinear spin vectors whereas "nspin=2"
> requires colinear spins, therefore, they would not work simultaneously.
> As a result, I can not use the "spin_component" keyword in the bands.x
> input file to extract the spin separated bands. So my question is: if I
> am using "lspinorb=.true." and "noncolin=.true.", is there a way to
> extract the spin-up and spin-down conduction and valence bands
> separately?
>
> Any help would be appreciated.
>
>
> Regards,
> Pratyush Manocha
> Graduate Student | M.S. Electrical & Computer Engineering
> School of Electrical and Computer Engineering
> Georgia Institute of Technology
> [cid:f2b1f8a4-9ef8-4579-9715-844bf6b1658b]
>
>


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