Dear Prof. Blaha, dear Gerhardt, Prof. Blaha, thank you for this detailed procedure :-)
I tried this today. What happens, is that nn and sgroup create *.struct file with space group 123, and 8 unique atoms (15 atoms total). The atoms on the opposite sides of the slab are merged into a single unique position. Calculation with SOC needs to have the atoms on the opposite sides of the slab splitted. However, initso_lapw does not split anything, and the *.struct (and *.struct_so) file stays pretty much the same as before, at least it again has only 8 unique atoms (15 total). As a result, after running SCF with SOC and sp I will not be able to separate the surface electronic structures on the opposite sites of the slab (along the in-plane axis orthogonal to the magnetization they will differ). Is it allowed/possible to use a primitive cell, and manually include the 2-fold rotation axis (which would be identical to the magnetization axis)? Regards, Lukasz On 12/13/2013 8:38 PM, Peter Blaha wrote: > Lets start "systematic". There's nothing simpler than creating > a (001) surface: > > Forget spin-orbit at the moment, just create a slab. > > Take a unit cell of bcc-Fe and > > x supercell with 1x1x7, add vacuum in z (eg. 30 bohr, your 15 bohr are a little too small) > and "repeat atom at z=0". > > Take the resulting struct file and run "several times" > x nn (always accept the created struct file). > x sgroup (sgroup will shift for you the positions, so that > you have a symmetric slab with inversion symmetry. > accept the struct file from sgroup). > > You can now do: > > init_lapw -b -sp -numk 400 (maybe with fermit 0.004, because we have > a 2D BZ and TETRA may have problems). > runsp -fc 1 converge and optimize positions (MSR1a). > > save_lapw > > Now you can run initso_lapw > Define magnetization direction and say "spin-polarization" yes. > This runs symmetso and depending on the direction of M it may/may not > reduce symmetry. Accept the structure and run > > runsp -I -so > > > Am 13.12.2013 18:28, schrieb [email protected]: >> Dear Gerhard, >> >> Thank you for your comment. >> >> I have a feeling, that my system has an inversion symmetry from the point >> of view of the electronic structure. If you think of surface electronic >> structure and surface Brillouin zone, then the surface electronic >> structures on both sides of the slab must be the same, only inverted with >> respect to surface-Gamma. The inversion is there, because in my particular >> case electronic structure is the same along the magnetization-axis and >> along minus-magnetization-axis. >> >> In any case (with or without inversion symmetry) the 180deg rotation >> around the magnetization axis is one of the symmetry operations of my >> slab. How can I include it in my calculation using the w2web interface? >> >> Regards, >> Lukasz >> >> >> >> SO has no inversion symmetry >> Think about the spin when you apply an inversion. >> >> Ciao >> Gerhard >> >> DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy: >> "I think the problem, to be quite honest with you, >> is that you have never actually known what the question is." >> >> ==================================== >> Dr. Gerhard H. Fecher >> Institut of Inorganic and Analytical Chemistry >> Johannes Gutenberg - University >> 55099 Mainz >> ________________________________________ >> Von: [email protected] >> [[email protected]]" im Auftrag von >> "[email protected] [[email protected]] >> Gesendet: Freitag, 13. Dezember 2013 18:02 >> An: [email protected] >> Betreff: Re: [Wien] Slab symmetry with SOC >> >> Dear Prof. Blaha, dear Wien2k users, >> >> I attach the most symmetric slab which I was able to produce. I try with >> 15 atoms in order to save time with testing, later I am planning to do a >> larger slab. You could see that now the surface normal is <100>, I started >> with <001>, but sgroup swapped axes -- but this is fine. So now the >> in-plane magnetization is along <001>, and it's the same as the mirror >> plane normal axis (becuase the space group is the 6_Pm with the unique >> c-axis). >> >> I believe that my system should have an inversion symmetry even with SOC. >> And at the same time I believe that the two surface atoms (in this case >> atom 1 and atom 15) should have their unique positions (they should not be >> merged into a single position as they would without SOC). >> >> I would appreciate the advice on how to make a spin-polarized calculation >> with SOC on this slab with included inversion symmetry. So far I have a >> mirror plane, so it would also be ok to only add a 2-fold 180deg rotation >> around the magnetization axis. >> >> Regards, >> Lukasz >> >> >> >> >> >> On 12/13/2013 11:22 AM, Peter Blaha wrote: >>> For a spin-polarized case you should use init_so and the program >> symmetso. Symmetso should give you the proper symmetries and one should >> use the struct file produced by symmetso. There should be a >> classification of each of the symmetry operations of the non-so case >> according to A, B or none. >>> >>> I can hardly comment on a specific feature without doing the slab myself. >>> >>> Please have a look into the lecture notes about spin-orbit coupling and >> the reduction of symmetry due to so (from our web-site). There is a plot >> and table for a small specific example. >>> >>> Hwoever, note two remarks: sgroup is completely irrelevant for this >> (as it does not know about spin-orbit). >>> >>> symmetso is obviously not as much tested as sgroup or symmetry. So be >> sure to use the latest version. >>> If you have doubts about symmetso, I need the struct file and the >> specific concerns. >>> >>> On 12/13/2013 10:00 AM, [email protected] wrote: >>>> Dear WIEN2k experts, >>>> >>>> Unfortunately nobody has commented on my email below. >>>> >>>> I believe that in my 15-atom Fe(001) slab, with magnetization along 100 >>>> and SOC included, there will be a mirror 100 plane (space group 6). >>>> However, I have a feeling that there are more symmetries. For example I >>>> have a feeling, that there should be an inversion symmetry, or at least >>>> that the 100 axis should be a two-fold rotation axis. I am not able to >>>> include these symmetries. >>>> >>>> My calculations work well with fully primitive cell, and also with space >>>> group 6 (actually sgroup rotates the slab, so that mirror plane becomes >>>> 001, but this of course does not matter). But I think that in every >>>> problem one should include the necessary symmetries a priori, not only to >>>> save time, but to avoid some spurious results. >>>> >>>> Could you please give me at least some hint? I could also send my slab if >>>> necessary. >>>> >>>> Regards, >>>> Lukasz >>>> >>>> >>>> >>>> >>>> >>>> On 12/5/2013 10:03 AM, [email protected] wrote: >>>> >>>> Dear WIEN2k experts, >>>> >>>> I am calculating 29-atom Fe(001) slab with SOC with easy axis along [100]. >>>> >>>> Without SOC one can find more symmetries, and one has only 15 inequivalent >>>> atoms. However, when performing the calculation with such slab the results >>>> are different compared to the complex calculation with "pure" slab of 29 >>>> atoms. I believe that the correct result in this calculation is that >>>> surface bands along [100] and [-100] are the same, and bands along [010] >>>> and [0-10] are different. So one should have 3 slightly different set of >>>> surface bands: along [100] (identical to [-100]), [010], and [0-10]. >>>> >>>> Of course on the opposite surfaces of the slab things will have the >>>> inversion symmetry. >>>> >>>> I believe that one of the programs, e.g. symmetso should in principle be >>>> able to find out, whether the symmetries are correct or not, and produce >>>> the correct struct file, which is possibly a bit more symmetric than the >>>> original file. >>>> >>>> Please advise. >>>> >>>> Regards, >>>> Lukasz >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Wien mailing list >>>> [email protected] >>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >>>> SEARCH the MAILING-LIST at: >> http://www.mail-archive.com/[email protected]/index.html >> >> >> -- >> Dr. Lukasz Plucinski >> _______________________________________________ >> Wien mailing list >> [email protected] >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> SEARCH the MAILING-LIST at: >> http://www.mail-archive.com/[email protected]/index.html >> >> >> >> _______________________________________________ >> Wien mailing list >> [email protected] >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html -- Dr. Lukasz Plucinski _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
