<div dir="auto"><div>Perhaps better to say that the ferromagnetic starting point converges to a ferromagnetic fixed point. You might be able to find a local ferromagnetic solution by first converging sonewhat using runfsm, then switching to runsp.<br><br><div data-smartmail="gmail_signature">---<br>Prof Laurence Marks<br>"Research is to see what everyone else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu">www.numis.northwestern.edu</a></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Apr 16, 2019, 09:53 Fecher, Gerhard <<a href="mailto:fecher@uni-mainz.de">fecher@uni-mainz.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">It just means that the ferromagnetic state is not stable,<br>
the solutions for the ferrimagnetic state are identical, besides the signs of the magnetic moments (what doesn't matter).<br>
<br>
Ciao<br>
Gerhard<br>
<br>
DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:<br>
"I think the problem, to be quite honest with you,<br>
is that you have never actually known what the question is."<br>
<br>
====================================<br>
Dr. Gerhard H. Fecher<br>
Institut of Inorganic and Analytical Chemistry<br>
Johannes Gutenberg - University<br>
55099 Mainz<br>
and<br>
Max Planck Institute for Chemical Physics of Solids<br>
01187 Dresden<br>
________________________________________<br>
Von: Wien [<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at" target="_blank" rel="noreferrer">wien-bounces@zeus.theochem.tuwien.ac.at</a>] im Auftrag von Penny, Charles [<a href="mailto:charles.penny11@imperial.ac.uk" target="_blank" rel="noreferrer">charles.penny11@imperial.ac.uk</a>]<br>
Gesendet: Dienstag, 16. April 2019 10:29<br>
An: <a href="mailto:wien@zeus.theochem.tuwien.ac.at" target="_blank" rel="noreferrer">wien@zeus.theochem.tuwien.ac.at</a><br>
Betreff: [Wien] Magnetic moments converging in a different direction to the one they are defined<br>
<br>
Dear all,<br>
<br>
<br>
I am running spin-polarised calculations on a range of iron-spinel structures (namely, magnetite (Fe3O4), maghemite (gamma-Fe2O3) and greigite (Fe3S4)) with the objective of calculating magnetic exchange energies in these minerals. This requires calculating total energies of lot of different spin configurations. This process has worked well for magnetite and maghemite, but I have encountered a problem with greigite.<br>
<br>
<br>
When I run a calculation on a spin configuration of greigite that isn’t the ferrimagnetic ground state (e.g. a ferromagnetic configuration) the calculation converges to the ferrimagnetic solution, with the sublattice moments pointing in opposing directions.<br>
<br>
<br>
In the examples below, I have used a low-symmetry unit cell with eight unique iron atoms which allows me to calculate the required number of spin configurations for estimating J_ij. Atoms 1-4 correspond to A site iron atoms in the spinel structure, atoms 5-8 correspond to B site iron atoms and atoms 9-16 are sulphur atoms. In a ferrimagnetic system the A and B sites have opposing moments and sulphur atoms are non-magneitc.<br>
<br>
<br>
When I define a ferrimagnetic spin configuration, the calculation proceeds as expected, with the final moments looking like;<br>
<br>
<br>
rkmax_8_k_500.scf::MMINT: MAGNETIC MOMENT IN INTERSTITIAL = -0.05116<br>
<br>
rkmax_8_k_500.scf::MMI001: MAGNETIC MOMENT IN SPHERE 1 = 2.47349<br>
<br>
rkmax_8_k_500.scf::MMI002: MAGNETIC MOMENT IN SPHERE 2 = 2.47348<br>
<br>
rkmax_8_k_500.scf::MMI003: MAGNETIC MOMENT IN SPHERE 3 = 2.47348<br>
<br>
rkmax_8_k_500.scf::MMI004: MAGNETIC MOMENT IN SPHERE 4 = 2.47348<br>
<br>
rkmax_8_k_500.scf::MMI005: MAGNETIC MOMENT IN SPHERE 5 = -3.01699<br>
<br>
rkmax_8_k_500.scf::MMI006: MAGNETIC MOMENT IN SPHERE 6 = -3.01699<br>
<br>
rkmax_8_k_500.scf::MMI007: MAGNETIC MOMENT IN SPHERE 7 = -3.01699<br>
<br>
rkmax_8_k_500.scf::MMI008: MAGNETIC MOMENT IN SPHERE 8 = -3.01699<br>
<br>
rkmax_8_k_500.scf::MMI009: MAGNETIC MOMENT IN SPHERE 9 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI010: MAGNETIC MOMENT IN SPHERE 10 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI011: MAGNETIC MOMENT IN SPHERE 11 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI012: MAGNETIC MOMENT IN SPHERE 12 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI013: MAGNETIC MOMENT IN SPHERE 13 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI014: MAGNETIC MOMENT IN SPHERE 14 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI015: MAGNETIC MOMENT IN SPHERE 15 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMI016: MAGNETIC MOMENT IN SPHERE 16 = -0.03675<br>
<br>
rkmax_8_k_500.scf::MMTOT: SPIN MAGNETIC MOMENT IN CELL = -14.88108<br>
<br>
<br>
Final energy;<br>
<br>
<br>
rkmax_8_k_500.scf::ENE : ********** TOTAL ENERGY IN Ry = -43322.30312592<br>
<br>
<br>
However, when I define a ferromagnetic spin configuration the system converges to a ferrimagnetic solution with final moments;<br>
<br>
<br>
k_500_rkmax_8.scf::MMINT: MAGNETIC MOMENT IN INTERSTITIAL = 0.05118<br>
<br>
k_500_rkmax_8.scf::MMI001: MAGNETIC MOMENT IN SPHERE 1 = -2.47348<br>
<br>
k_500_rkmax_8.scf::MMI002: MAGNETIC MOMENT IN SPHERE 2 = -2.47347<br>
<br>
k_500_rkmax_8.scf::MMI003: MAGNETIC MOMENT IN SPHERE 3 = -2.47346<br>
<br>
k_500_rkmax_8.scf::MMI004: MAGNETIC MOMENT IN SPHERE 4 = -2.47346<br>
<br>
k_500_rkmax_8.scf::MMI005: MAGNETIC MOMENT IN SPHERE 5 = 3.01697<br>
<br>
k_500_rkmax_8.scf::MMI006: MAGNETIC MOMENT IN SPHERE 6 = 3.01697<br>
<br>
k_500_rkmax_8.scf::MMI007: MAGNETIC MOMENT IN SPHERE 7 = 3.01697<br>
<br>
k_500_rkmax_8.scf::MMI008: MAGNETIC MOMENT IN SPHERE 8 = 3.01697<br>
<br>
k_500_rkmax_8.scf::MMI009: MAGNETIC MOMENT IN SPHERE 9 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI010: MAGNETIC MOMENT IN SPHERE 10 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI011: MAGNETIC MOMENT IN SPHERE 11 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI012: MAGNETIC MOMENT IN SPHERE 12 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI013: MAGNETIC MOMENT IN SPHERE 13 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI014: MAGNETIC MOMENT IN SPHERE 14 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI015: MAGNETIC MOMENT IN SPHERE 15 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMI016: MAGNETIC MOMENT IN SPHERE 16 = 0.03675<br>
<br>
k_500_rkmax_8.scf::MMTOT: SPIN MAGNETIC MOMENT IN CELL = 14.88103<br>
<br>
<br>
Final energy is the same as in the ferrimagnetic case;<br>
<br>
<br>
k_500_rkmax_8.scf::ENE : ********** TOTAL ENERGY IN Ry = -43322.30312578<br>
<br>
<br>
Charge distance looks like it converges in both cases. Note that whilst the two calculations have the same saved name, they are in completely different CASE files. To outline my procedure, I initially call,<br>
<br>
<br>
instgen -ask<br>
<br>
<br>
And define the moments as ‘u u u u u u u u n n n n n n n n’ for a ferromagnetic calculation and ‘u u u u d d d d n n n n n n n n’ for a ferrimagnetic calculation.<br>
<br>
<br>
Then,<br>
<br>
<br>
init -b -sp -numk 500 -rkmax 8.00<br>
<br>
runsp -ec 0.0001 -cc 0.0001 -fc 1.0 -p -i 200<br>
<br>
<br>
I am at a loss as to what is going on and can’t find anything in the mailing list to explain this. Any help on this matter would be greatly appreciated.<br>
<br>
<br>
Regards,<br>
<br>
<br>
Charlie<br>
<br>
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</blockquote></div></div></div>