Hi Jaroslav, with SO, 001 is not equivalent to 001 or 010, if the magnetisation is along 001 this you see easily from the changed symmetry after initializing SO (symmetso)
regards from Dresden 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 and Max Planck Institute for Chemical Physics of Solids 01187 Dresden ________________________________________ Von: Wien [[email protected]] im Auftrag von Jaroslav Hamrle [[email protected]] Gesendet: Freitag, 24. November 2017 16:36 An: [email protected] Betreff: [Wien] different MLD for bcc structure for magnetic equivalent directions M001, M010 and M100 Dear colleagues, We have found non-physical asymmetry related with equivalent magnetization directions, when calculating electronic structure for bcc Fe: We want to calculate magnetic linear dichroism, MLD, defined as a difference between diagonal permittivity element being parallel, perpendicular to direction of magnetization, respectively. MLD=epzz - (epxx+epyy)/2 for M001 MLD=epyy - (epxx+epzz)/2 for M010 MLD=epxx - (epyy+epzz)/2 for M100 Obviously, MLD calculated for different equivalent magnetization directions should be identical. But they are not, MLD calculated for 001 is different to MLD calculated for 010 and 100 (MLD for 010 and 100 are identical). In most cases, we used k-mesh 30x30x30, exgange LDA (choice 5), with convergence criteria runsp_lapw -so -cc 0.000001 -ec 0.0000001 -s lapw1 and the convergence was reached. * We tested this asymmetry also for fcc structures (Ni, Co, Co2MnSi). We also tested simple cubic structure (bcc Fe, defined as a simple cubic structure with two Fe atoms). In all those cases, the asymmetry disappears. On the other hand, it also appeared also in bcc Ni. Hence, the asymmetry seems to be specifically related with bcc structure. * this asymmetry can be observed already in energy levels (files case.energysoup). Hence, we think, the asymmetry is not a feature of optics. Namely, there is a very good agreement for energies for M010 and M100 (in example below difference is below 2e-7Ry), but much bigger difference between energies for M001 and (M010,M100) (in example below max. difference is 18e-6 Ry for band 5). Therefore it seems that this problem arises in either lapw0 or lapw1 for bcc structure. To demonstrate the difference, we show energy levels for the first k-point (in vicinity of the Gamma point shifted in 111 direction from the Gamma point): Fe30M001: 0.333333333333E-01 0.333333333333E-01 0.333333333333E-01 1 55 18 8.0 1 -3.4390104377017581 2 -3.4064979309023942 3 -3.3508627657180750 4 -3.2276472567243979 5 -3.1955089683446780 6 -3.1702455400854954 7 -7.1658179115217727E-002 8 -4.3723732810772589E-002 9 0.37296762299903474 10 0.37521967189559313 Fe30M010: 0.333333333333E-01 0.333333333333E-01 0.333333333333E-01 1 55 18 8.0 1 -3.4390110394480322 2 -3.4064968725403300 3 -3.3508644682352022 4 -3.2276486274720977 5 -3.1954902103327028 6 -3.1702472318057655 7 -7.1659013996950252E-002 8 -4.3723316415832839E-002 9 0.37296632778787425 10 0.37521816821120640 Fe30M100: 0.333333333333E-01 0.333333333333E-01 0.333333333333E-01 1 55 18 8.0 1 -3.4390109925234049 2 -3.4064968346346225 3 -3.3508643700301919 4 -3.2276485335559135 5 -3.1954901707639891 6 -3.1702471600962974 7 -7.1658839213425571E-002 8 -4.3723135315494835E-002 9 0.37296642179994044 10 0.37521826479385562 The difference in energy is (in micro-Ry): left column E(001)-E(100), right column E(010)-E(100) 1 0.5548 -0.0469 2 -1.0963 -0.0379 3 1.6043 -0.0982 4 1.2768 -0.0939 5 -18.7976 -0.0396 6 1.6200 -0.0717 7 0.6601 -0.1748 8 -0.5975 -0.1811 9 1.2012 -0.0940 10 1.4071 -0.0966 clearly, energies for M001 are different from those for M010 and M100. * We checked also similar calculation by elk code. Here the asymmetry in optical spectra is not present. On the other hand, it is presented and equals in all wien2k versions 14-17. Similar asymmetry is also present when testing equivalent directions of types 110 and 111 directions in bcc Fe. * calculations were done for k-point mesh 30x30x30, but the same symmetry/asymmetry appears from k-mesh 10x10x10 to mesh 40x40x40. With increasing k-mesh density, the asymmetry somewhat decreases. All other parameters to calculate bcc Fe were default parameters. Any help how to remove this equivalent-magnetization-direction asymmetry is very welcome. With my best regards Jaroslav Hamrle Ondřej Stejskal PS: We attach some spectral dependences of MLD on bcc Fe related to previous text: http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/MLD_Fe30.pdf MLD calculated for Fe30 (meaning bcc Fe with k-mesh 30x30x30), showing unphysical optical anisotropy for equivalent magnetization direction. Particularly notice peak around 4.8 eV, which looks artificial and has opposite sign for M001 and (M010, M100). http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/MLD_Fe46.pdf MLD on Fe46 (notice, peak at 4.8eV has smaller amplitude) http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/MLD_Fe30-as_simple_cubic.pdf MLD on Fe30, where bcc Fe is calculated as simple cubic structure containing two Fe atoms. In this case, the asymmetry disappears. http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/MLD_Fe30-elk.pdf To compare, MLD calculated by code elk does not provide previously discussed anisotropy. http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/MLD_Fe_compareall.pdf Figure showing all previously mentioned MLD together. details of calculations can be found: http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/Fe30M001 http://alma.karlov.mff.cuni.cz/hamrle/w2kfig/Fe30M100 PSS: there is a small bug in script 'x join_vectorfiles -so -up' The script requires file case.in1c, which is not created and not needed for all other calculations. Anyway, 'cp case.in1 case.in1c' solves the problem. -- ------------------------------------------------------------------ Mgr. Jaroslav Hamrle, Ph.D. Institute of Physics, room F232 Faculty of Mathematics and Physics Charles University Ke Karlovu 5 121 16 Prague Czech Republic tel: +420-95155 1340 email: [email protected] ------------------------------------------------------------------ _______________________________________________ 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
