### Re: [Wien] Is there an effect of SO on the ground state

In the way of a comment I only can repeat what has been explained several times in this mailing list: Take care to calculate all energies you want to compare with exactly the same parameters: same structural unit cell, same number of k-vectors, same Rkmax etc. and be careful to check that convergence with number of k-vectors, and Rkmax is better than the energy differences you get for the magnetic structures. Between the calculations only the orientation of the moments should differ. This means you calculate ALL energies with the largest unit cell of lowest symmetry to keep the size of the primitve cell constant. You told us that you already did the comparison of PM, FM, AF1, AF2,and AF3 without SO. Did you do this in the above way? Was the calculated magnetic structure with minimum energy the experimental one? Estimate the exchange constants J from the energy differences. Are they reasonable? Good luck with the calculations, Martin Pieper --- Dr. Martin Pieper Karl-Franzens University Institute of Physics Universitätsplatz 5 A-8010 Graz Austria Tel.: +43-(0)316-380-8564 Am 31.10.2016 19:53, schrieb Abderrahmane Reggad: Thank you Dr Pieper for the detailed and fruitful information. For my compound with the hexagonal structure, I know beforehand the magnetic ground structure which is still hexagonal with magnetic order AF1, but for the 2 other magnetic structures for AF2 and AF3 , they become orthorhombic. Since the inclusion of the SO interaction affects the magnetic ground state, I will add it to exhibit the magnetic ground structure for my compound. I need your comment on the different magnetic structures for my compound and the effect of the inclusion of SO interaction on them. Best regards Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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

### Re: [Wien] Is there an effect of SO on the ground state

Thank you Dr Pieper for the detailed and fruitful information. For my compound with the hexagonal structure, I know beforehand the magnetic ground structure which is still hexagonal with magnetic order AF1, but for the 2 other magnetic structures for AF2 and AF3 , they become orthorhombic. Since the inclusion of the SO interaction affects the magnetic ground state, I will add it to exhibit the magnetic ground structure for my compound. I need your comment on the different magnetic structures for my compound and the effect of the inclusion of SO interaction on them. Best regards Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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

### Re: [Wien] Is there an effect of SO on the ground state

Of course inclusion of SO interactions may lead to another magnetic ground state. For example, at least in principle it certainely will do so if the symmetry of your Hamiltonian including SO breaks some symmetry of the ground state you found without SO. So you might want to look wether or not initso induces changes of your symmetry. However, the effect in whatever you are interested in might be too small to make a real difference. Therefore, you also might compare typical SO interaction energies for elements in your structure with the energy differences between the ground states you worked out without SO. If you have light elements (small SO) and large Heisenberg exchange, then probably nothing will happen. In addition you should be aware of the fact that Wien2k (or any other DFT program) will find (if you are lucky and everything works out) the ground state within the symmetry you set up during initialization. If you set up a hexagonal structure with some AF magnetic structure on top of it (maybe in a larger unit cell) your result from the scf cycle will have that symmetry. The actual ground state of the material you are interested in might be completely different. A drastic example: SO interaction may lead to non-collinear helical spin structures - which are outside the scope of standard Wien2k. --- Dr. Martin Pieper Karl-Franzens University Institute of Physics Universitätsplatz 5 A-8010 Graz Austria Tel.: +43-(0)316-380-8564 Am 30.10.2016 14:55, schrieb Abderrahmane Reggad: Thanks Dr pieper for the rich information within your answer. Perhaps I didn't formulated my question well . I am not interesting exactly to the ground state energy , but to the magnetic ground state. As I mentionned before , I want to determine the magnetic ground state from 5 configurations: nm,fm, afm1,afm2 and afm3 for hexagonal crystal structure (NiAs structure exatly); and I want to know if the inclusion or not of the SO coupling affect this magnetic ground state.i.e. without SO , I got a magnetic ground state , and if I include the SO, may be this leads to another magnetic ground state. Best regards -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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

### Re: [Wien] Is there an effect of SO on the ground state

Thanks Dr pieper for the rich information within your answer. Perhaps I didn't formulated my question well . I am not interesting exactly to the ground state energy , but to the magnetic ground state. As I mentionned before , I want to determine the magnetic ground state from 5 configurations: nm,fm, afm1,afm2 and afm3 for hexagonal crystal structure (NiAs structure exatly); and I want to know if the inclusion or not of the SO coupling affect this magnetic ground state.i.e. without SO , I got a magnetic ground state , and if I include the SO, may be this leads to another magnetic ground state. Best regards -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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

### Re: [Wien] Is there an effect of SO on the ground state

My 2 cents to this: Not a particularly meaningful question. The only meaningful thing about energies, as in eigenvalues of the Hamiltonian, is their DIFFERENCE. The evolution with time of the state of an isokated quantum system (Schrödinger picture) is completely governed by the differences of the eigenvalues of the Hamiltonian. The choice of where you put zero is up to you. A common choice for zero is the ground state energy of the Hamiltonian. In this case clearly zero is zero, there is no effect of SO. Other choices are more practical in various circumstances: The mean of the spektrum of the Hamiltonian, or the Fermi energy (definition discussed recently here), or some fictitious reference limit like the state with all charges at infinite distance ... The ground state energy then probably will depend on whether or not you put SO into your Hamiltonian. After all you consider SO because it changes energy differences and might split degeneracies. --- Dr. Martin Pieper Karl-Franzens University Institute of Physics Universitätsplatz 5 A-8010 Graz Austria Tel.: +43-(0)316-380-8564 Am 29.10.2016 23:20, schrieb Abderrahmane Reggad: Hello again I am waiting for an answer to my question . My question is about the effect of the inclusion of the Spin-Orbit Coupling on the ground state energy. I want to know if the SO affect the ground state energy also or It only causes the splitting of the degenerate state energies. Any information will be fruitful for me. I hope find an answer to my question -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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

### Re: [Wien] Is there an effect of SO on the ground state

Hello again I am waiting for an answer to my question . My question is about the effect of the inclusion of the Spin-Orbit Coupling on the ground state energy. I want to know if the SO affect the ground state energy also or It only causes the splitting of the degenerate state energies. Any information will be fruitful for me. I hope find an answer to my question -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ 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