[QE-users] How to extract the px, py, pz, dz2, ....contributions with SOC from projdos out

Pietro Davide Delugas pdelugas at sissa.it
Mon Jul 5 12:13:50 CEST 2021


Dear Elie
keeping in mind the caveat of Thomas you could  in fact "cheat" projwfc 
in projecting your eigenstates into the non-relatistic atomic states 
labeled with l and the spin (up or down along z).
You just have to open the xml restart file ( the one inside  the 
prefix.save directory) look for the output element and, inside it,  the 
magnetization element,
there change the <spinorbit> element from true to false.

hope this helps
Pietro





On 7/4/21 8:37 PM, Elio Physics wrote:
> Dear Thomas,
>
> Thank you for the generous and detailed answer. Indeed, what made me 
> confused is that some papers still use the terminology "dz2' ,for 
> example, even in the presence of the SOC. I will definitely be looking 
> at the papers you suggested to decide which option I will adopt for 
> the discussion I need.
>
> Regards
>
> ------------------------------------------------------------------------
> *From:* Thomas Brumme <tbrumme at msx.tu-dresden.de>
> *Sent:* Sunday, July 4, 2021 10:24 AM
> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>; 
> Elio Physics <Elio-Physics at live.com>
> *Subject:* Re: [QE-users] How to extract the px, py, pz, dz2, 
> ....contributions with SOC from projdos out
>
> Dear Elie,
>
>
> The short answer is: You can't!
>
>
> Spin-orbit interaction couples the orbital angular momentum with the 
> spin momentum and thus neither l or s are good quantum number anymore. 
> You now have to use the total angular momentum J. Sure, a lot of 
> people still use the nomenclature from the non-SOC calculations, such 
> as speaking in the case of 2D TMDCs of dz² states at the K point, but 
> strictly speaking this is not correct. If you really want to 
> understand the relation between J and L in detail, I can recommend the 
> paper by Andrea Dal Corso and Adriano Mosca Conte, Phys. Rev. B 71, 
> 115106 (2005) (https://link.aps.org/doi/10.1103/PhysRevB.71.115106 
> <https://link.aps.org/doi/10.1103/PhysRevB.71.115106>) which nicely 
> shows which spherical harmonics are included in which spin-angle 
> functions for which total angular momentum j. If I remember this 
> correctly (some time ago that I did this and I can't find the table 
> anymore) the states with higher mj (+-3/2 and +- 5/2) have more 
> in-plane characterfor both j=3/5 and j=5/2 (i.e., the contain terms 
> with spherical harmonics which are usually combined such that the 
> result is in the xy-plane) while the states with mj=+-1/2 have more 
> out-of-plane character (z direction). But I could be wrong here since 
> I don't have the details anymore.
>
>
> The only option for you - if you don't want to check the paper or if 
> this is too much and if nobody else comments here - is to do a non-SOC 
> calculation and then hope that SOC is not mixing states too much and 
> you can still call the result, e.g., dz² like. OR you plot the 
> corresponding wave function in real space and decide by "looking" at 
> the form of |psi|².
>
>
> Regards
>
>
> Thomas
>
>
>
> P.S.: another detail concerning, e.g., the states at K in a WS2 
> monolayer - is this your system? :)
>
> The states are not simple split into spin up and spin down even if a 
> lot of people use this nomenclature. For the valence band the two 
> SOC-split bands are to nearly 100% spin up or down but not for the 
> conduction band where you won't have states which are 100% up or down, 
> even if there is no in-plane contribution... Some details can also be 
> found here: https://link.aps.org/doi/10.1103/PhysRevB.101.235408 
> <https://link.aps.org/doi/10.1103/PhysRevB.101.235408>
>
>
> On 7/4/21 6:52 AM, Elio Physics wrote:
>> Dear all,
>>
>> I am studying the contribution of the orbitals to the bands of a 
>> structure, in the presence of spin orbit coupling. At the beginning 
>> of the projwfc.x output file, I got:
>>
>>      state #   1: atom   1 (S  ), wfc  1 (l=0 j=0.5 m_j=-0.5)
>>      state #   2: atom   1 (S  ), wfc  1 (l=0 j=0.5 m_j= 0.5)
>>      state #   3: atom   1 (S  ), wfc  2 (l=1 j=0.5 m_j=-0.5)
>>      state #   4: atom   1 (S  ), wfc  2 (l=1 j=0.5 m_j= 0.5)
>>      state #   5: atom   1 (S  ), wfc  3 (l=1 j=1.5 m_j=-1.5)
>>      state #   6: atom   1 (S  ), wfc  3 (l=1 j=1.5 m_j=-0.5)
>>      state #   7: atom   1 (S  ), wfc  3 (l=1 j=1.5 m_j= 0.5)
>>      state #   8: atom   1 (S  ), wfc  3 (l=1 j=1.5 m_j= 1.5)
>> .
>> .
>> .
>>       state #  39: atom   5 (W ), wfc  3 (l=2 j=1.5 m_j=-1.5)
>>      state #  40: atom   5 (W), wfc  3 (l=2 j=1.5 m_j=-0.5)
>>      state #  41: atom   5 (W), wfc  3 (l=2 j=1.5 m_j= 0.5)
>>      state #  42: atom   5 (W), wfc  3 (l=2 j=1.5 m_j= 1.5)
>>      state #  43: atom   5 (W ), wfc  4 (l=2 j=2.5 m_j=-2.5)
>>      state #  44: atom   5 (W ), wfc  4 (l=2 j=2.5 m_j=-1.5)
>>      state #  45: atom   5 (W), wfc  4 (l=2 j=2.5 m_j=-0.5)
>>      state #  46: atom   5 (W), wfc  4 (l=2 j=2.5 m_j= 0.5)
>>      state #  47: atom   5 (W), wfc  4 (l=2 j=2.5 m_j= 1.5)
>>
>> The l=1 wavefunctions are the p contributions. But How can we 
>> specifically identify which one is px, py and pz?
>> Similary, how to identify which ones of the 10 d orbitals are the 
>> dz^2 for example
>>
>> regards
>>
>> Elie
>> Federal Universiy of Rondonia
>> Brazil
>>
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> -- 
> Dr. rer. nat. Thomas Brumme
> Theoretical chemistry
> TU Dresden - BAR / II49
> Helmholtzstr. 18
> 01069 Dresden
>
> Tel:  +49 (0)351 463 40844
>
> email:thomas.brumme at tu-dresden.de  <mailto:thomas.brumme at tu-dresden.de>
>
> _______________________________________________
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