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Dear Professor Luiz,</div>
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Got it. Thank you very much! <br>
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<div style="font-size: 12pt; color: black;" data-ogsc="black"><b><span style="font-family: Arial, Helvetica, sans-serif; color: rgb(153, 0, 0);" data-ogsc="rgb(153, 0, 0)">R</span><span style="font-family: Arial, Helvetica, sans-serif; color: rgb(153, 0, 0);" data-ogsc="rgb(153, 0, 0)">egards,</span></b>
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<div><span style="font-family:Arial,Helvetica,sans-serif"><b>Pratyush Manocha</b></span></div>
<div><span style="font-family:Arial,Helvetica,sans-serif">Graduate Student | M.S. Electrical & Computer Engineering</span><span style="font-family:Arial,Helvetica,sans-serif"><br>
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<div><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-family: Arial, Helvetica, sans-serif; font-weight: normal; background-color: white;" data-ogsb="white">School of Electrical and Computer Engineering</span><br>
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<b><span style="font-family: Arial, Helvetica, sans-serif; color: rgb(179, 163, 105);">Georgia</span></b><span style="font-family:Arial,Helvetica,sans-serif"> Institute of
</span><b><span style="font-family: Arial, Helvetica, sans-serif; color: rgb(179, 163, 105);">Tech</span></b><span style="font-family:Arial,Helvetica,sans-serif">nology</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Luiz Gustavo Davanse da Silveira <lgsilveira@fisica.ufpr.br><br>
<b>Sent:</b> Thursday, March 23, 2023 10:16<br>
<b>To:</b> Manocha, Pratyush <pmanocha@gatech.edu><br>
<b>Cc:</b> users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
<b>Subject:</b> Re: [QE-users] Requesting Help With Spin Orbit Coupling Spin-Separated Bands Extraction</font>
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<div class="PlainText">Dear Pratyush Manocha,<br>
<br>
> I'm repeating this just for clarity. So, "lsigma = 1,2,3" would give me<br>
> the expectation values of the spin operator along the cartesian<br>
> coordinate axes, x, y, and z, right?<br>
<br>
Right.<br>
<br>
> How would I go about doing this? Is it possible to do this on Quantum<br>
> Espresso itself? I don't think doing this would hold any value because<br>
> the spin-up direction is also changing as the spin axis is changing.<br>
> However, if the spin vector in the band is aligned in the local spin-up<br>
> direction at all points along the k-path, it would be considered the<br>
> spin-up band. So, I would like to learn how to compute it to increase my<br>
> understanding of the system.<br>
<br>
It doesn't. But since "lsigma" gives you the three orthogonal vector<br>
components, by using regular vector properties you can obtain the polar<br>
and azimuthal angles. As I said in my previous e-mail, if you are<br>
interested in identifying spin polarized bands, using a color scale to<br>
express spin components values on a band structure plot should give you<br>
the information you need without much hassle.<br>
<br>
Best regards,<br>
<br>
Luiz Gustavo Silveira<br>
Assistant professor, Department of Physics - Federal University of Paraná<br>
Curitiba - Brazil<br>
<br>
Em Qua, Março 22, 2023 8:08 pm, Manocha, Pratyush escreveu:<br>
> Dear Professor Luiz,<br>
><br>
><br>
> Thank you for your response. I have a couple of more questions.<br>
><br>
><br>
>> It gives you the expectation values of the spin operator.<br>
>><br>
><br>
>> Simply put, "lsigma = 1,2,3" gives you the three orthogonal components<br>
>> of the spin vector.<br>
><br>
> I'm repeating this just for clarity. So, "lsigma = 1,2,3" would give me<br>
> the expectation values of the spin operator along the cartesian<br>
> coordinate axes, x, y, and z, right?<br>
><br>
>> You could, in principle, determine which direction this is and define<br>
>> locally what is spin up and spin down, I don't know if it's worth it,<br>
>> though.<br>
><br>
> How would I go about doing this? Is it possible to do this on Quantum<br>
> Espresso itself? I don't think doing this would hold any value because<br>
> the spin-up direction is also changing as the spin axis is changing.<br>
> However, if the spin vector in the band is aligned in the local spin-up<br>
> direction at all points along the k-path, it would be considered the<br>
> spin-up band. So, I would like to learn how to compute it to increase my<br>
> understanding of the system.<br>
><br>
>> But if the bands are splitted and spin-polarized you will end up with a<br>
>> graph showing something similar to spin-up and spin-down bands.<br>
> Got it.<br>
><br>
><br>
> Regards,<br>
> Pratyush Manocha<br>
> Graduate Student | M.S. Electrical & Computer Engineering<br>
> School of Electrical and Computer Engineering<br>
> Georgia Institute of Technology<br>
> [cid:55e08a0f-cc73-4d36-8b82-45ea4b522d9d]<br>
> ________________________________<br>
> From: Luiz Gustavo Davanse da Silveira <lgsilveira@fisica.ufpr.br><br>
> Sent: Monday, March 20, 2023 16:25<br>
> To: Manocha, Pratyush <pmanocha@gatech.edu><br>
> Cc: users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
> Subject: Re: [QE-users] Requesting Help With Spin Orbit Coupling<br>
> Spin-Separated Bands Extraction<br>
><br>
><br>
> Dear Pratyush Manocha,<br>
><br>
><br>
> Now I'm the one who has to apologize about a delayed response.<br>
><br>
><br>
>> Thank you for informing me about the "lsigma" keyword. While it doesn't<br>
>> solve my problem of segregating spin-up bands from spin-down ones, it<br>
>> gives me the expectation values of the total angular momentum along the<br>
>> x, y, and z axes, right?<br>
><br>
> It gives you the expectation values of the spin operator.<br>
><br>
><br>
>> I tried extracting the data for GaAs, and I noticed from the results<br>
>> that often, the expectation values are values other than 0.5, 0, and<br>
>> -0.5;<br>
>> does this mean that, at these points, the band has a mix of both spin-up<br>
>> and spin-down electrons?<br>
><br>
> Well, you might find sources that describe it like that, but, as I see<br>
> it, in noncollinear calculations each electronic state can have its own<br>
> spin quantization axis. Therefore, global spin-up and spin-down states may<br>
> not be a good description. Rather, depending on the complexity of your<br>
> system, at each k-point of a given band spins may be align in a particular<br>
> direction. You could, in principle, determine which direction this is<br>
> and define locally what is spin up and spin down, I don't know if it's<br>
> worth it, though. Simply put, "lsigma = 1,2,3" gives you the three<br>
> orthogonal components of the spin vector. If you take the modulus, the<br>
> result should be 0.5 (or close to it).<br>
><br>
>> Another question I had is: when you say that I can color the bands<br>
>> according to the spin values like a fatband plot, do you mean that each<br>
>> band would individually be coloured from "colour a" to "colour b" based<br>
>> on the spin values at the different k points along the chosen<br>
>> "k-path?"<br>
>><br>
><br>
> Exactly. This form of showing the data might not be useful if bands are<br>
> degenerate. But if the bands are splitted and spin-polarized you will end<br>
> up with a graph showing something similar to spin-up and spin-down bands.<br>
><br>
><br>
> Best regards,<br>
><br>
><br>
> Luiz Gustavo Silveira<br>
> Assistant professor, Department of Physics - Federal University of Paraná<br>
> Curitiba - Brazil<br>
><br>
><br>
><br>
> Em Qui, Março 9, 2023 11:47 pm, Manocha, Pratyush escreveu:<br>
><br>
>> Dear Professor Luiz,<br>
>><br>
>><br>
>><br>
>> I apologize for my delayed response; I had exams to appear for.<br>
>><br>
>><br>
>><br>
>> Thank you for informing me about the "lsigma" keyword. While it doesn't<br>
>> solve my problem of segregating spin-up bands from spin-down ones, it<br>
>> gives me the expectation values of the total angular momentum along the<br>
>> x, y, and z axes, right?<br>
>><br>
>> I tried extracting the data for GaAs, and I noticed from the results<br>
>> that often, the expectation values are values other than 0.5, 0, and<br>
>> -0.5;<br>
>> does this mean that, at these points, the band has a mix of both spin-up<br>
>> and spin-down electrons?<br>
>><br>
>> Another question I had is: when you say that I can color the bands<br>
>> according to the spin values like a fatband plot, do you mean that each<br>
>> band would individually be coloured from "colour a" to "colour b" based<br>
>> on the spin values at the different k points along the chosen<br>
>> "k-path?"<br>
>><br>
>><br>
>> Thank you very much for helping me with this!<br>
>><br>
>><br>
>><br>
>> Regards,<br>
>> Pratyush Manocha<br>
>> Graduate Student | M.S. Electrical & Computer Engineering<br>
>> School of Electrical and Computer Engineering<br>
>> Georgia Institute of Technology<br>
>> ________________________________<br>
>> From: Luiz Gustavo Davanse da Silveira <lgsilveira@fisica.ufpr.br><br>
>> Sent: Thursday, February 16, 2023 14:03<br>
>> To: Manocha, Pratyush <pmanocha@gatech.edu><br>
>> Cc: users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
>> Subject: Re: [QE-users] Requesting Help With Spin Orbit Coupling<br>
>> Spin-Separated Bands Extraction<br>
>><br>
>><br>
>><br>
>> Dear Pratyush Manocha,<br>
>><br>
>><br>
>><br>
>> I believe the spin_component variable doesn't work with noncollinear<br>
>> calculations. You can however use the lsigma variable in bands.x input<br>
>> to get the spin components at each k-point for every band. Then, for<br>
>> instance, you can use this information to color the band plot according<br>
>> to spin values (like a fatbands plot).<br>
>><br>
>> Best Regards,<br>
>><br>
>><br>
>><br>
>> Luiz Gustavo Silveira<br>
>> Assistant professor, Department of Physics - Federal University of<br>
>> Paraná<br>
>> Curitiba - Brazil<br>
>><br>
>><br>
>><br>
>> Em Seg, Dezembro 19, 2022 7:22 pm, Manocha, Pratyush escreveu:<br>
>><br>
>><br>
>>> Dear All,<br>
>>><br>
>>><br>
>>><br>
>>><br>
>>> I am using QE-7.1 and want to plot the spin-orbit coupled bands for<br>
>>> Silicon and later on, GaN. I ran a few simulations for Silicon (with a<br>
>>> fully relativistic pseudopotential obtained from PSLibrary 1.0.0) by<br>
>>> turning on the "lspinorb" and "noncolin" keywords and specifying a<br>
>>> non-zero "starting_magnetization" in the "&system" namecard. The<br>
>>> simulation runs smoothly, however, when I try to extract the bands<br>
>>> for just spin-down electrons using "spin_component=2" in the input<br>
>>> file given to the bands.x code, it returns the following error: Error<br>
>>> in routine punch_bands (1): incorrect spin_component???.<br>
>>><br>
>>> I went through the archive and also tried simulating with various<br>
>>> different keyword combinations using "nspin" and "lspinorb", and I<br>
>>> found that "lspinorb" requires non-colinear spin vectors whereas<br>
>>> "nspin=2"<br>
>>> requires colinear spins, therefore, they would not work<br>
>>> simultaneously. As a result, I can not use the "spin_component"<br>
>>> keyword in the bands.x input file to extract the spin separated bands.<br>
>>> So my question is: if<br>
>>> I<br>
>>> am using "lspinorb=.true." and "noncolin=.true.", is there a way to<br>
>>> extract the spin-up and spin-down conduction and valence bands<br>
>>> separately?<br>
>>><br>
>>> Any help would be appreciated.<br>
>>><br>
>>><br>
>>><br>
>>><br>
>>> Regards,<br>
>>> Pratyush Manocha<br>
>>> Graduate Student | M.S. Electrical & Computer Engineering<br>
>>> School of Electrical and Computer Engineering<br>
>>> Georgia Institute of Technology<br>
>>> [cid:f2b1f8a4-9ef8-4579-9715-844bf6b1658b]<br>
>>><br>
>>><br>
>>><br>
>>><br>
>><br>
>><br>
>><br>
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