[Wien] Magnetic moments converging in a different direction to the one they are defined

[Laurence Marks]

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.

---
Prof Laurence Marks
"Research is to see what everyone else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu

On Tue, Apr 16, 2019, 09:53 Fecher, Gerhard <fecher at uni-mainz.de> wrote:

> It just means that the ferromagnetic state is not stable,
> the solutions for the ferrimagnetic state are identical, besides the signs
> of the magnetic moments (what doesn't matter).
>
> 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 [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von Penny,
> Charles [charles.penny11 at imperial.ac.uk]
> Gesendet: Dienstag, 16. April 2019 10:29
> An: wien at zeus.theochem.tuwien.ac.at
> Betreff: [Wien] Magnetic moments converging in a different direction to
> the one they are defined
>
> Dear all,
>
>
> 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.
>
>
> 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.
>
>
> 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.
>
>
> When I define a ferrimagnetic spin configuration, the calculation proceeds
> as expected, with the final moments looking like;
>
>
> rkmax_8_k_500.scf::MMINT:  MAGNETIC MOMENT IN INTERSTITIAL  =   -0.05116
>
> rkmax_8_k_500.scf::MMI001: MAGNETIC MOMENT IN SPHERE   1    =    2.47349
>
> rkmax_8_k_500.scf::MMI002: MAGNETIC MOMENT IN SPHERE   2    =    2.47348
>
> rkmax_8_k_500.scf::MMI003: MAGNETIC MOMENT IN SPHERE   3    =    2.47348
>
> rkmax_8_k_500.scf::MMI004: MAGNETIC MOMENT IN SPHERE   4    =    2.47348
>
> rkmax_8_k_500.scf::MMI005: MAGNETIC MOMENT IN SPHERE   5    =   -3.01699
>
> rkmax_8_k_500.scf::MMI006: MAGNETIC MOMENT IN SPHERE   6    =   -3.01699
>
> rkmax_8_k_500.scf::MMI007: MAGNETIC MOMENT IN SPHERE   7    =   -3.01699
>
> rkmax_8_k_500.scf::MMI008: MAGNETIC MOMENT IN SPHERE   8    =   -3.01699
>
> rkmax_8_k_500.scf::MMI009: MAGNETIC MOMENT IN SPHERE   9    =   -0.03675
>
> rkmax_8_k_500.scf::MMI010: MAGNETIC MOMENT IN SPHERE  10    =   -0.03675
>
> rkmax_8_k_500.scf::MMI011: MAGNETIC MOMENT IN SPHERE  11    =   -0.03675
>
> rkmax_8_k_500.scf::MMI012: MAGNETIC MOMENT IN SPHERE  12    =   -0.03675
>
> rkmax_8_k_500.scf::MMI013: MAGNETIC MOMENT IN SPHERE  13    =   -0.03675
>
> rkmax_8_k_500.scf::MMI014: MAGNETIC MOMENT IN SPHERE  14    =   -0.03675
>
> rkmax_8_k_500.scf::MMI015: MAGNETIC MOMENT IN SPHERE  15    =   -0.03675
>
> rkmax_8_k_500.scf::MMI016: MAGNETIC MOMENT IN SPHERE  16    =   -0.03675
>
> rkmax_8_k_500.scf::MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =  -14.88108
>
>
> Final energy;
>
>
> rkmax_8_k_500.scf::ENE  : ********** TOTAL ENERGY IN Ry =
>  -43322.30312592
>
>
> However, when I define a ferromagnetic spin configuration the system
> converges to a ferrimagnetic solution with final moments;
>
>
> k_500_rkmax_8.scf::MMINT:  MAGNETIC MOMENT IN INTERSTITIAL  =    0.05118
>
> k_500_rkmax_8.scf::MMI001: MAGNETIC MOMENT IN SPHERE   1    =   -2.47348
>
> k_500_rkmax_8.scf::MMI002: MAGNETIC MOMENT IN SPHERE   2    =   -2.47347
>
> k_500_rkmax_8.scf::MMI003: MAGNETIC MOMENT IN SPHERE   3    =   -2.47346
>
> k_500_rkmax_8.scf::MMI004: MAGNETIC MOMENT IN SPHERE   4    =   -2.47346
>
> k_500_rkmax_8.scf::MMI005: MAGNETIC MOMENT IN SPHERE   5    =    3.01697
>
> k_500_rkmax_8.scf::MMI006: MAGNETIC MOMENT IN SPHERE   6    =    3.01697
>
> k_500_rkmax_8.scf::MMI007: MAGNETIC MOMENT IN SPHERE   7    =    3.01697
>
> k_500_rkmax_8.scf::MMI008: MAGNETIC MOMENT IN SPHERE   8    =    3.01697
>
> k_500_rkmax_8.scf::MMI009: MAGNETIC MOMENT IN SPHERE   9    =    0.03675
>
> k_500_rkmax_8.scf::MMI010: MAGNETIC MOMENT IN SPHERE  10    =    0.03675
>
> k_500_rkmax_8.scf::MMI011: MAGNETIC MOMENT IN SPHERE  11    =    0.03675
>
> k_500_rkmax_8.scf::MMI012: MAGNETIC MOMENT IN SPHERE  12    =    0.03675
>
> k_500_rkmax_8.scf::MMI013: MAGNETIC MOMENT IN SPHERE  13    =    0.03675
>
> k_500_rkmax_8.scf::MMI014: MAGNETIC MOMENT IN SPHERE  14    =    0.03675
>
> k_500_rkmax_8.scf::MMI015: MAGNETIC MOMENT IN SPHERE  15    =    0.03675
>
> k_500_rkmax_8.scf::MMI016: MAGNETIC MOMENT IN SPHERE  16    =    0.03675
>
> k_500_rkmax_8.scf::MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =   14.88103
>
>
> Final energy is the same as in the ferrimagnetic case;
>
>
> k_500_rkmax_8.scf::ENE  : ********** TOTAL ENERGY IN Ry =
>  -43322.30312578
>
>
> 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,
>
>
> instgen -ask
>
>
> 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.
>
>
> Then,
>
>
> init -b -sp -numk 500 -rkmax 8.00
>
> runsp -ec 0.0001 -cc 0.0001 -fc 1.0 -p -i 200
>
>
> 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.
>
>
> Regards,
>
>
> Charlie
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
>
> https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwIF-g&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=67AVCnoLm7SPw-Ve2jCL6O7AZBFCNcLhTUFNw_dPuS0&s=4P8zji_3Bsaz5VC5k3QGIsLGO0L8U_c_fWRmGPdrt-U&e=
> SEARCH the MAILING-LIST at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwIF-g&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=67AVCnoLm7SPw-Ve2jCL6O7AZBFCNcLhTUFNw_dPuS0&s=1fBJRUzGxLUo3u00OikWQUjgucDu9KeAABZY09-7_Ic&e=
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20190416/c23b6aed/attachment.html>