I would be interested in clarification from others, but from what I can see in the code it appears that this is the spin direction that is used, not just the direction of breaking the symmetry. I may be wrong.
On Tue, May 5, 2015 at 11:47 AM, pieper <pie...@ifp.tuwien.ac.at> wrote: > I definitely am not an expert for -so, therefore I will not shoot down > anything, only a comment: > > From my point of view from magnetism I would ask for some caution with > identifying the direction given in .inorb and .inso with 'the spin > direction'. As Gerhard pointed out earlier in this thread, it's all > about symmetry: The specified direction only sets up the symmetry of the > case to be compatibel with whatever has a rotational invariance with > that (quantization) axis - be that a spin, or orbital moment, > magnetization, a magnetic field, ... The symmetry of the basis has to > allow for a magnetization otherwise it won't appear when you calculate > expectation values. Personally I find Pavel's 'lecture on spin-orbit.ps' > here in the Wien documentation files (I hope it's still there) very > illuminating. > > > > --- > Dr. Martin Pieper > Karl-Franzens University > Institute of Physics > Universitätsplatz 5 > A-8010 Graz > Austria > Tel.: +43-(0)316-380-8564 > > > Am 05.05.2015 14:51, schrieb Laurence Marks: > > Me a culpa, I should have checked the mailing list first for the > > answers. > > > > That said, this issue has come up enough times in the past that I > > think the UG should be tweaked so it is clearer. Let me try my > > interpretation, so I can be shot down if needed. > > > > Within Wien2k magnetic effects can be approximately included in a > > number of ways. Some such as the spin-orbit coupling assume a > > direction for the spin vector (for all electrons actively considered), > > others such as Bext in orb specify a direction for an applied magnetic > > field (in Tesla) and use the same direction for the spin vector. (The > > two spin states are then either parallel or anti parallel to the > > specified direction.) When a direction is specified in case.inso or > > case.inorb this fixes the spin vector and (if used) the external > > magnetic field direction. Via the output files from lapwdm > > (case.scfdmXX) one can monitor how the angular momentum changes [1]. > > By using different directions for the spin vector (and field) one can > > probe how the energy changes and/orbital occupancies with assumed > > directions for the spin/external magnetic field. > > > > To escape the assumption that the spin vectors all have one direction > > the Wienncm code has to be used. > > > > [1] My addendum. Changes in the occupancies can be a soft electronic > > mode, i.e. very small changes in the energy for quite large changes in > > the density. The older mixing algorithms (MSEC1 or MSEC3) are not so > > good for soft modes and can stagnate. MSR1 is better and the next > > release (7.0) is much better. With onsite -eece &/or -orb it may help > > to "push" the mixer by either forcing a larger step (echo .2 > .msec > > or echo .1 > .pratt) or stopping, doing a force on the orbital > > potential (x orb -up; x orb -dn) then restarting with -NI. It is > > probably wise to check how the orbital momentum is converging (grep > > :ORB0 *.scf, perhaps other) and make sure that the mixing is not > > starving (grep GREED: *.scf and check the values are not small, e.g. > > 0.035). > > > > ___________________________ > > Professor Laurence Marks > > Department of Materials Science and Engineering > > Northwestern University > > www.numis.northwestern.edu [1] > > MURI4D.numis.northwestern.edu [2] > > Co-Editor, Acta Cryst A > > "Research is to see what everybody else has seen, and to think what > > nobody else has thought" > > Albert Szent-Gyorgi > > On May 4, 2015 6:22 PM, "Laurence Marks" <l-ma...@northwestern.edu> > > wrote: > > > >> Typo: > >> > >> "although I remember don't symmetry operations being split into > >> these two classes everywhere in the code" > >> > >> On Mon, May 4, 2015 at 6:04 PM, Laurence Marks > >> <l-ma...@northwestern.edu> wrote: > >> > >>> I am a newbie at -so, so a few simple questions. > >>> > >>> a) What is the meaning of the orbital moment in case.scfdm* ? Is > >>> that the average direction projected to the global axis system? > >>> > >>> b) What is the physical significance of the orbital moment being > >>> parallel (or not quite parallel) to the direction used in > >>> case.inso? > >>> > >>> c) I understand that the results for different directions of B in > >>> case.inso reflect the magnetic anisotropy, but what are the units > >>> of field (if any)? > >>> > >>> d) What else is worth looking at? The partial orbital moment > >>> (:POM) seems relevant, but what exactly is it? > >>> > >>> e) I am "blindly" trusting that initso knows what it is doing, and > >>> have left the "B" symmetry operations in case.struct (although I > >>> remember symmetry operations being split into these two classes > >>> everywhere in the code). This seems to conflict with Pavel's > >>> notes, although those may be too old. > >>> > >>> Thanks. > >>> > >>> -- > >>> > >>> Professor Laurence Marks > >>> Department of Materials Science and Engineering > >>> Northwestern University > >>> www.numis.northwestern.edu [1] > >>> Corrosion in 4D: MURI4D.numis.northwestern.edu [2] > >>> Co-Editor, Acta Cryst A > >>> "Research is to see what everybody else has seen, and to think > >>> what nobody else has thought" > >>> Albert Szent-Gyorgi > >> > >> -- > >> > >> Professor Laurence Marks > >> Department of Materials Science and Engineering > >> Northwestern University > >> www.numis.northwestern.edu [1] > >> Corrosion in 4D: MURI4D.numis.northwestern.edu [2] > >> Co-Editor, Acta Cryst A > >> "Research is to see what everybody else has seen, and to think what > >> nobody else has thought" > >> Albert Szent-Gyorgi > > > > > > Links: > > ------ > > [1] http://www.numis.northwestern.edu > > [2] http://MURI4D.numis.northwestern.edu > > > > _______________________________________________ > > Wien mailing list > > Wien@zeus.theochem.tuwien.ac.at > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > SEARCH the MAILING-LIST at: > > http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: > http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: MURI4D.numis.northwestern.edu Co-Editor, Acta Cryst A "Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Gyorgi
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