Re: [Wien] [SPAM?] Should the valence electrons configuration of charge transfer insulators be changed ?
I'll add a few statements about core-EELS: 1) Core hole: In principle we want to simulate the excitation of ONE core electron into the conduction band. Thus one should create a big supercell (as big as possible, at least 64 atoms) and put a full core hole (I guess this was NOT yet mentioned, but is the most important point of the discussion !). This hole will be partially screened, and with our limited supercell size and the static DFT approximation, this screening could be incomplete and thus one sometimes uses "empirically" 1/2 or no core hole (in particular for metals) at all. This is an often used method, but of course it is no longer "ab initio". 2) Slaters transistion state is a well known concept to calculate the XPS binding energy of a core state, where you would remove the excited electron from the system (it comes out and goes to the detector). It has NOTHING to do in EELS , where the excited electron stays in the system (except if you would attempt to calculate the absolute energy of an edge). 3) excited electron: In principle it is clear that the excited electron should go into a dipole allowed conduction band state. However, we have NO MEANS to select such a state and the electron will go into the first empty states in the system in a scf procedure.If we feel that this state is not the state where it would go in experiment, it is better to put the electron into the "background" charge (mixer). E.g in NiO the O-1s electron should go into a O-2p state. However, the first conduction bands are Ni-d states in the supercell calculation and thus adding an electron to the valence electrons is not appropriate. In the case of cuprates, I'd probably add it to the valence, since the "hole" state is a mixture of Cu-d-x2-y2 - O-2p and thus at least partly it is ok to put the electron into it. In any case, I'd do the calculation with both, adding the electron to valence or to background. 4) spin state: It is of course clear, that the photon does not change the spin state of the excited electron.In a spin-polarized calculation when you put the electron into the valence, it is usually obeyed anyway, because the missing core electron of "spin-up" will lower the potential of spin-up and the electron will go into the spin-up conduction bands, preserving the total spin of the system. However, correlations within the conduction bands could change this anyway, because the "other electrons" could react on the presence of an additional spin-up electron.This is in particular true for correlated TM oxides. And if you use the background-option, the spin.state is not defined anyway, since the background option cannot be done spin-selective. In non-spinpolarized calculations it should not really matter. Am 17.11.2019 um 14:58 schrieb ??: As we all know, DFT deals with the system in the ground state. When dealing with the charge transfer insulator system, can I modify the valence electronic configuration after initialization and before SCF and EELS (Electron Energy Loss Spectroscopy) calculations ? The Cu-based high temperature superconducting (HTSC) oxides are known to be insulators of a charge-transfer type, with the charge-transfer (CT) gap originating from the energy difference between the O(2p) and the Cu(3dx2-y2) orbitals. Before calculating EELS of Cu-based HTSC oxides, will it make the result reasonable if their valence electron configuration is changed ? For example, we remove one oxygen 2p electron and add one electron in Cu 3d orbit. Just like the treatment of core hole effect. For a ??core-hole?? calculation we will edit super.inc and remove one core electron from the desired atom and state (1s or 2p, ...). Then we add the missing electron either in super.inm (background charge) or super.in2 (add it to the valence electrons). This problem haunts me for several weeks, and my question is still unsolved after consulting the previous mailing list. Any comment(s) would be highly appreciated. Thanks in advance! ___ 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 -- -- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-165300 FAX: +43-1-58801-165982 Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at WWW: http://www.imc.tuwien.ac.at/tc_blaha- ___ 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] [SPAM?] Should the valence electrons configuration of charge transfer insulators be changed ?
Respected Prof. Marks, In the EELS calculation literature I have read, many do not involve the topic of spin. I probably understand it after reading your reply, thank you for your patient and earnest explanation, and I will use runfsm to finish the following calculation. I have just visited your research group website at Northwestern University, there are so many publications and honors. A very diligent and outstanding scientist. Thank you so much! Best wishes ! Yifan Ding (Ph.D candidate) Institute of Physics, Chinese Academy of Science (CAS) Address: No.8 Zhongguancun South 3rd Street, Haidian District, Beijing 100190 China E-mail: yfding0...@foxmail.com ___ 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] Beween non spin polarized and spin polarized calculations
Thanks xavier for the interesting article and useful information My new question is : what's the relationship between the unpaired electrons and the orbital contribution. I think that the unpaired electrons are always related to the spin contribution. Best regards -- Dr. Abderrahmane Reggad Engineering Physics Laboratory Faculty of Material Sciences, Ibn Khaldoun University, Tiaret, 14000, Algeria Tel: +213(0)561861963 - Algeria ___ 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] Should the valence electrons configuration of charge transfer insulators be changed ?
I strongly suggest that you research the basis for the Slater 1/2 method as well as extensions. What Slater suggested is that an integral from the initial state (no core hole) and the final state (complete core hole) could be approximated by the midpoint (1/2 core hole). One can do better, albeit it will take more calculations, for instance consider more fractional holes (e.g. 1/4, 3/4) then integrate better. No core hole assumes that your switch electron has passed before the system can respond -- which is dubious because the temporal coherence (width along the beam direction) is large, typically 100nm or so. A full core hole assumes that the swift electron hangs around for a long time so sees more of the final state, also not a very convincing argument for current microscopes. (Let's ignore femtosecond EM.) N.B., describing the swift electron correctly via mutual coherence (effectively a density matrix) is not common. We had a go in Ultramicroscopy 55 (1994) 165 at the spatial description, if you dig you may find papers where the temporal part has been included. I have not fully tracked the literature on this. At least in standard models, the initial and final spin states should be the same -- exchange coupling of a TEM electron and the solid is essentially zero. (With SOC I am not sure exactly what should be done.) I am not aware of calculations where this constraint has been enforced, although there may be some. (I have checked this myself for some transition metal oxides and it matters.) I very strongly suspect that in some of the literature calculations the final spin-state differs from the original, so the results have a buried incorrect approximation. Thus, if you take 1/2 (or other) electrons out of the core then in my opinion you need to ensure that the initial and final spin states (all electrons) are the same, e.g. use runfsm. Unfortunately you might still have a different local spin state which at least at present Wien2k cannot handle. On Sun, Nov 17, 2019 at 9:41 AM 丁一凡 wrote: > Respected Prof. Marks, > > I remember 1/2 core hole calculations in this article "Partial core hole > screening in the Cu L-3 edge" (DOI:10.1007/s100510170179). When calculating > my systems, I only used a full core hole and supercell. I will follow your > suggestion and try it. In the previous calculation, I didn't notice the > relation between spin and core hole. Please allow me to ask a question > here, why is runfsm the best method ? > ___ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=IaYA9EMobH_kt7vz-PIZQe9kfpg3FT2--xUJQ2Ab52I&s=VAJEsdWNwMXjnX7a6vqaWdmGZZ0LxAyqLZiCi-twZKM&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=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=IaYA9EMobH_kt7vz-PIZQe9kfpg3FT2--xUJQ2Ab52I&s=bIndfEmmbUY8Vn29vIBEfrrBcS1ufsDySR2edvgq9uc&e= > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI 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 ___ 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] Should the valence electrons configuration of charge transfer insulators be changed ?
Respected Prof. Marks, I remember 1/2 core hole calculations in this article "Partial core hole screening in the Cu L-3 edge" (DOI:10.1007/s100510170179). When calculating my systems, I only used a full core hole and supercell. I will follow your suggestion and try it. In the previous calculation, I didn't notice the relation between spin and core hole. Please allow me to ask a question here, why is runfsm the best method ? ___ 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] Should the valence electrons configuration of charge transfer insulators be changed ?
For O, I will suggest using a 1/2 hole in the O 1K core state. A tricky problem (which I do not have a full answer for) is what spin to use for the core hole, and also the best method to avoid changes of spin-state (e.g. runfsm). On Sun, Nov 17, 2019 at 9:04 AM 丁一凡 wrote: > Respected Prof. Marks, > > Thanks for your so quick reply! This method may not be suitable for me. > My TEM experiment data are core-loss spectra (O K EELS). I want to simulate > EELS that is consistent with the experiment, but I have not done it so far > (perhaps because of charge transfer). I have downloaded the PRM paper and > am reading them. > ___ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=JttOKIjEf1VP7WGsNCrpm3QfckiTsQq3JOL8gc0egSo&s=i1y2BFTuGNNaRSmD-juF4f-1gq4i15xJknjbQXlVBrU&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=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=JttOKIjEf1VP7WGsNCrpm3QfckiTsQq3JOL8gc0egSo&s=-M5Rb-AP_RK4gu9tX1DNo0ZriKIsnDfXs-30relocA0&e= > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI 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 ___ 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] Should the valence electrons configuration of charge transfer insulators be changed ?
Respected Prof. Marks, Thanks for your so quick reply! This method may not be suitable for me. My TEM experiment data are core-loss spectra (O K EELS). I want to simulate EELS that is consistent with the experiment, but I have not done it so far (perhaps because of charge transfer). I have downloaded the PRM paper and am reading them.___ 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] [SPAM?] Should the valence electrons configuration of charge transfer insulators be changed ?
To my knowledge, the closest you can come is the LDA 1/2 method, and/or LDA (or GGA) +U. These are related to what is called the "Slater-Janak transition state approach", although not many people use it. My group found it useful for VXPS spectra of some lanthanides, see DOI: 10.1103/PhysRevMaterials.2.025001. However, I am not sure that this is appropriate for EELS, unless you are using low energy electrons (e.g. 1-100 eV). For standard core-loss EELS the changes when using a Slater approach are so large that they will probably swamp these effects. Also important for conventional EELS are standard channelling issues -- to my knowledge no code currently can correctly include both the dynamical diffraction terms and the solid-state transition terms with full rigor. On Sun, Nov 17, 2019 at 7:59 AM 丁一凡 wrote: > As we all know, DFT deals with the system in the ground state. When > dealing with the charge transfer insulator system, can I modify the valence > electronic configuration after initialization and before SCF and EELS > (Electron Energy Loss Spectroscopy) calculations ? > > The Cu-based high temperature superconducting (HTSC) oxides are known to > be insulators of a charge-transfer type, with the charge-transfer (CT) gap > originating from the energy difference between the O(2p) and the > Cu(3dx2-y2) orbitals. Before calculating EELS of Cu-based HTSC oxides, will > it make the result reasonable if their valence electron configuration is > changed ? For example, we remove one oxygen 2p electron and add one > electron in Cu 3d orbit. Just like the treatment of core hole effect. For a > “core-hole” calculation we will edit super.inc and remove one core electron > from the desired atom and state (1s or 2p, ...). Then we add the missing > electron either in super.inm (background charge) or super.in2 (add it to > the valence electrons). > > This problem haunts me for several weeks, and my question is still > unsolved after consulting the previous mailing list. Any comment(s) would > be highly appreciated. Thanks in advance! > ___ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=FNBOlFHjZKxWOUE7JbFz8Euj1d26nwaUGP96FSpj_v8&s=qvSVWjM2sFOW6misH9dhI-lUUqKZmN2Ux2Xawt-pD3k&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=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=FNBOlFHjZKxWOUE7JbFz8Euj1d26nwaUGP96FSpj_v8&s=go40WrwaP622LVcgRSe_KrfAwQdcBNY6aynFxWuswYo&e= > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI 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 ___ 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] [SPAM?] Should the valence electrons configuration of charge transfer insulators be changed ?
As we all know, DFT deals with the system in the ground state. When dealing with the charge transfer insulator system, can I modify the valence electronic configuration after initialization and before SCF and EELS (Electron Energy Loss Spectroscopy) calculations ? The Cu-based high temperature superconducting (HTSC) oxides are known to be insulators of a charge-transfer type, with the charge-transfer (CT) gap originating from the energy difference between the O(2p) and the Cu(3dx2-y2) orbitals. Before calculating EELS of Cu-based HTSC oxides, will it make the result reasonable if their valence electron configuration is changed ? For example, we remove one oxygen 2p electron and add one electron in Cu 3d orbit. Just like the treatment of core hole effect. For a ??core-hole?? calculation we will edit super.inc and remove one core electron from the desired atom and state (1s or 2p, ...). Then we add the missing electron either in super.inm (background charge) or super.in2 (add it to the valence electrons). This problem haunts me for several weeks, and my question is still unsolved after consulting the previous mailing list. Any comment(s) would be highly appreciated. Thanks in advance!___ 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] Beween non spin polarized and spin polarized calculations
I recommend you the following article: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.108.047201 Bulk gold is diamagnetic and it exhibits a tiny Pauli and Orbital paramagnetic state. Pauli paramagnetism is due to the non-zero density at the Fermi level (metal) and the orbital paramagnetism to the presence of unpaired electrons. Best regards Xavier Le 16/11/2019 à 20:59, Abderrahmane Reggad a écrit : Since the ground state of the Au metal is non magnetic, does it mean that the Au metal is diamagnetic or paramagnetic and why ? -- Dr. Abderrahmane Reggad Engineering Physics Laboratory Faculty of Material Sciences, Ibn Khaldoun University, Tiaret, 14000, Algeria Tel: +213(0)561861963 - Algeria ___ 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 -- Institut des Sciences Chimiques de Rennes (ISCR) Univ Rennes - CNRS - UMR6226, France https://iscr.univ-rennes1.fr/cti/people/permanent-staff/rocquefelte-xavier ICAMM2019 : VASP Workshop and International Materials Modelling Conf June 26-July 3 2019, Rennes France icamm2019.sciencesconf.org : Registration opening soon, see you there! ___ 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
