Re: [Wien] d-eg orbitals are not effected by applying Ueff
From the abstract of the paper you cited in your last mail I gather that this an alloy. So I suspect that there is some cite disorder with Co as well as Ga occupying the lattice sites randomly? In that case Co would have a number of different configurations, due to the random distribution, that are not represented in your .struct file. As for the gap: This was a question, not stating some fact. Unfortunately I did not follow the literature on GGA+U, so I am not aware of any studies with the same problem as yours. But I am also not aware of any study saying that a (reasonably sized) U MUST produce a gap. Here the real experts might provide more useful comments. Best regards, Martin Pieper --- Dr. Martin Pieper Karl-Franzens University Institute of Physics Universitätsplatz 5 A-8010 Graz Austria Tel.: +43-(0)316-380-8564 Am 28.01.2017 01:21, schrieb venkatesh chandragiri: Dear Prof. Pieper, the answers are as follows, I UNDERSTAND THAT THIS IS AN ALLOY? IF YES, WHAT KIND OF SUPERCELL DO YOU USE TO MODEL THE SYSTEM? I do not used any supercell configuration. The case.struct file contains the two atoms as given below. ARE THESE T2G AND EG SYMMETRIES ACTUALLY PRESENT IN ALL POSSIBLE CONFIGURATIONS WITHIN THE ALLOY (PROBABLY NOT)? IS IT POSSIBLE THAT THE SYMMETRY YOU ARTIFICIALLY IMPOSE IS AT THE BOTTOM OF THIS? Experimentally, at room temperature, we have refined the crystal structure of the Co50Ga50 alloy and the same used for the generating the case.struct. I do not understand the your meaning of " all possible configurations ". WHY DO YOU BELIEVE THAT U SHOULD ACT IN THE SAME WAY ON DIFFERENT SYMMETRIES? COULD IT BE THAT LOCALIZING T2G PAYS OFF MUCH BETTER THAN EG? I do not have experience before on the DFT +U studies, but have seen in literature that one could create artifical energy gap by applying U in order to explain the insulating behaviour of few oxides. It would be helpful for me, if you provide me some references where the localizing t2g pays off much better than eg by applying U. DID YOU TRY OTHER CONFIGURATIONS / SUPERCELLS / SYMMETRIES? I tried DFT + SO + U , but this also leads to the same feature in DOS like DFT + U case. No supercells are tried. Could you please suggest me next step or possible configurations so that I can give a try. thanks for your reply and looking forward to your help venkatesh === Co50Ga50.struct === Co50Ga50 P LATTICE,NONEQUIV.ATOMS: 2 221_Pm-3m MODE OF CALC=RELA unit=bohr 5.438632 5.438632 5.438632 90.00 90.00 90.00 ATOM 1: X=0. Y=0. Z=0. MULT= 1 ISPLIT= 2 Ga1 NPT= 781 R0=0.5000 RMT= 2.2400 Z: 31.0 LOCAL ROT MATRIX: 1.000 0.000 0.000 0.000 1.000 0.000 0.000 0.000 1.000 ATOM 2: X=0.5000 Y=0.5000 Z=0.5000 MULT= 1 ISPLIT= 2 Co1 NPT= 781 R0=0.5000 RMT= 2.3500 Z: 27.0 LOCAL ROT MATRIX: 1.000 0.000 0.000 0.000 1.000 0.000 0.000 0.000 1.000 48 NUMBER OF SYMMETRY OPERATIONS -1 0 0 0. 0-1 0 0. 0 0-1 0. 1 -1 0 0 0. 0-1 0 0. 0 0 1 0. 2 -1 0 0 0. 0 0-1 0. 0-1 0 0. 3 -1 0 0 0. 0 0 1 0. 0-1 0 0. 4 -1 0 0 0. 0 0-1 0. 0 1 0 0. 5 -1 0 0 0. 0 0 1 0. 0 1 0 0. 6 -1 0 0 0. 0 1 0 0. 0 0-1 0. 7 -1 0 0 0. 0 1 0 0. 0 0 1 0. 8 0-1 0 0. -1 0 0 0. 0 0-1 0. 9 0-1 0 0. -1 0 0 0. 0 0 1 0. 10 0 0-1 0. -1 0 0 0. 0-1 0 0. 11 0 0 1 0. -1 0 0 0. 0-1 0 0. 12 0 0-1 0. -1 0 0 0. 0 1 0 0. 13 0 0 1 0. -1 0 0 0. 0 1 0 0. 14 0 1 0 0. -1 0 0 0. 0 0-1 0. 15 0 1 0 0. -1 0 0 0. 0 0 1 0. 16 0-1 0 0. 0 0-1 0. -1 0 0 0. 17 0-1 0 0. 0 0 1 0. -1 0 0 0. 18 0 0-1 0. 0-1 0 0. -1 0 0 0. 19 0 0 1 0. 0-1 0 0. -1 0 0 0. 20 0 0-1 0. 0 1 0 0. -1 0 0 0. 21 0 0 1 0. 0 1 0 0. -1 0 0 0. 22 0 1 0 0. 0 0-1 0. -1 0 0 0. 23 0 1 0 0. 0 0 1 0. -1 0 0 0. 24 0-1 0 0. 0 0-1 0. 1 0 0 0.
Re: [Wien] d-eg orbitals are not effected by applying Ueff
Dear Prof. Pieper, the answers are as follows, *I understand that this is an alloy? If yes, what kind of supercell do you use to model the system?* I do not used any supercell configuration. The case.struct file contains the two atoms as given below. *Are these t2g and eg symmetries actually present in all possible configurations within the alloy (probably not)? Is it possible that the symmetry you artificially impose is at the bottom of this?* Experimentally, at room temperature, we have refined the crystal structure of the Co50Ga50 alloy and the same used for the generating the case.struct. I do not understand the your meaning of " all possible configurations ". *Why do you believe that U should act in the same way on different symmetries? Could it be that localizing t2g pays off much better than eg?* I do not have experience before on the DFT +U studies, but have seen in literature that one could create artifical energy gap by applying U in order to explain the insulating behaviour of few oxides. It would be helpful for me, if you provide me some references where the localizing t2g pays off much better than eg by applying U. *Did you try other configurations / supercells / symmetries? * I tried DFT + SO + U , but this also leads to the same feature in DOS like DFT + U case. No supercells are tried. Could you please suggest me next step or possible configurations so that I can give a try. thanks for your reply and looking forward to your help venkatesh === Co50Ga50.struct === Co50Ga50 P LATTICE,NONEQUIV.ATOMS: 2 221_Pm-3m MODE OF CALC=RELA unit=bohr 5.438632 5.438632 5.438632 90.00 90.00 90.00 ATOM 1: X=0. Y=0. Z=0. MULT= 1 ISPLIT= 2 Ga1NPT= 781 R0=0.5000 RMT=2.2400 Z: 31.0 LOCAL ROT MATRIX:1.000 0.000 0.000 0.000 1.000 0.000 0.000 0.000 1.000 ATOM 2: X=0.5000 Y=0.5000 Z=0.5000 MULT= 1 ISPLIT= 2 Co1NPT= 781 R0=0.5000 RMT=2.3500 Z: 27.0 LOCAL ROT MATRIX:1.000 0.000 0.000 0.000 1.000 0.000 0.000 0.000 1.000 48 NUMBER OF SYMMETRY OPERATIONS -1 0 0 0. 0-1 0 0. 0 0-1 0. 1 -1 0 0 0. 0-1 0 0. 0 0 1 0. 2 -1 0 0 0. 0 0-1 0. 0-1 0 0. 3 -1 0 0 0. 0 0 1 0. 0-1 0 0. 4 -1 0 0 0. 0 0-1 0. 0 1 0 0. 5 -1 0 0 0. 0 0 1 0. 0 1 0 0. 6 -1 0 0 0. 0 1 0 0. 0 0-1 0. 7 -1 0 0 0. 0 1 0 0. 0 0 1 0. 8 0-1 0 0. -1 0 0 0. 0 0-1 0. 9 0-1 0 0. -1 0 0 0. 0 0 1 0. 10 0 0-1 0. -1 0 0 0. 0-1 0 0. 11 0 0 1 0. -1 0 0 0. 0-1 0 0. 12 0 0-1 0. -1 0 0 0. 0 1 0 0. 13 0 0 1 0. -1 0 0 0. 0 1 0 0. 14 0 1 0 0. -1 0 0 0. 0 0-1 0. 15 0 1 0 0. -1 0 0 0. 0 0 1 0. 16 0-1 0 0. 0 0-1 0. -1 0 0 0. 17 0-1 0 0. 0 0 1 0. -1 0 0 0. 18 0 0-1 0. 0-1 0 0. -1 0 0 0. 19 0 0 1 0. 0-1 0 0. -1 0 0 0. 20 0 0-1 0. 0 1 0 0. -1 0 0 0. 21 0 0 1 0. 0 1 0 0. -1 0 0 0. 22 0 1 0 0. 0 0-1 0. -1 0 0 0. 23 0 1 0 0. 0 0 1 0. -1 0 0 0. 24 0-1 0 0. 0 0-1 0. 1 0 0 0. 25 0-1 0 0. 0 0 1 0. 1 0 0 0. 26 0 0-1 0. 0-1 0 0. 1 0 0 0. 27 0 0 1 0. 0-1 0 0. 1 0 0 0. 28 0 0-1 0. 0 1 0 0. 1 0 0 0. 29 0 0 1 0. 0 1 0 0. 1 0 0 0. 30 0 1 0 0. 0 0-1 0. 1 0 0 0. 31 0 1 0 0. 0 0 1 0. 1 0 0 0. 32 0-1 0 0. 1 0 0 0. 0 0-1 0. 33 0-1 0 0. 1 0 0 0. 0 0 1 0. 34 0 0-1 0. 1 0 0 0. 0-1 0 0. 35 0 0 1 0. 1 0 0 0. 0-1 0 0. 36 0 0-1 0. 1 0 0 0. 0 1 0 0. 37 0 0 1 0. 1 0 0 0. 0 1 0 0. 38 0 1 0 0. 1 0 0 0. 0 0-1 0. 39 0 1 0 0. 1 0 0 0. 0 0 1 0. 40 1 0 0 0. 0-1 0 0. 0 0-1 0. 41 1 0 0 0. 0-1 0 0. 0 0 1 0. 42 1 0 0 0. 0 0-1
Re: [Wien] d-eg orbitals are not effected by applying Ueff
Not really a comment, just a few questions one might consider (I probably would, but I am half an expert at best): I understand that this is an alloy? If yes, what kind of supercell do you use to model the system? Are these t2g and eg symmetries actually present in all possible configurations within the alloy (probably not)? Is it possible that the symmetry you artificially impose is at the bottom of this? Why do you believe that U should act in the same way on different symmetries? Could it be that localizing t2g pays off much better than eg? Did you try other configurations / supercells / symmetries? Best regards, Martin Pieper --- Dr. Martin Pieper Karl-Franzens University Institute of Physics Universitätsplatz 5 A-8010 Graz Austria Tel.: +43-(0)316-380-8564 Am 26.01.2017 19:17, schrieb venkatesh chandragiri: Dear Prof. Lyudmila Dobysheva Thanks for your reply. There was a old paper on this alloy, which show similar kind of results, ie. deep pseudo gap with finite states at Ef. please see the link below http://iopscience.iop.org/article/10.1088/0305-4608/12/2/009/meta [1] In this article they discussed the raise in resitivity using the Mott theory of electron localization when electrons are captured by these states around Ef, so called localised states. However, I want to apply U for the Co-d states in order to explain the raise in resistivity at low temperatures by creating artificial gap. But although, I applied U= 5 eV on Co-d states, d-t2g states are only moved well below the Fermi level while d-eg are not effected. This leads to presence of finite states from d-eg at Ef. please share any idea you have about this.. Can someone has any another comment on this..? thanks venkatesh Links: -- [1] http://iopscience.iop.org/article/10.1088/0305-4608/12/2/009/meta ___ 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] d-eg orbitals are not effected by applying Ueff
Dear Prof. Lyudmila Dobysheva Thanks for your reply. There was a old paper on this alloy, which show similar kind of results, ie. deep pseudo gap with finite states at Ef. please see the link below http://iopscience.iop.org/article/10.1088/0305-4608/12/2/009/meta In this article they discussed the raise in resitivity using the Mott theory of electron localization when electrons are captured by these states around Ef, so called localised states. However, I want to apply U for the Co-d states in order to explain the raise in resistivity at low temperatures by creating artificial gap. But although, I applied U= 5 eV on Co-d states, d-t2g states are only moved well below the Fermi level while d-eg are not effected. This leads to presence of finite states from d-eg at Ef. please share any idea you have about this.. Can someone has any another comment on this..? thanks venkatesh ___ 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] d-eg orbitals are not effected by applying Ueff
25.01.2017 20:43, venkatesh chandragiri wrote: I want to explain the negative temperature co-efficient of Co50Ga50 alloy using DFT. For this, I have run the SCF calculation using experimental XRD parameters with simple spin polarized case. I am not familiar with this problem so very quick and maybe wrong comment: the substance looks magnetic, some papers in a search say about magnetic properties and "giant" Co magnetic moment. You show nonmagnetic DOS, though made spin polarized. Maybe this is a reason why you cannot obtain the gap? I'd start from a search on earlier calculations of the system. Best wishes Lyudmila Dobysheva -- Phys.-Techn. Institute of Ural Br. of Russian Ac. of Sci. 426001 Izhevsk, ul.Kirova 132 RUSSIA -- Tel.:7(3412) 432045(office), 722529(Fax) E-mail: l...@ftiudm.ru, lyuk...@mail.ru (office) lyuk...@gmail.com (home) Skype: lyuka17 (home), lyuka18 (office) http://ftiudm.ru/content/view/25/103/lang,english/ -- ___ 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] d-eg orbitals are not effected by applying Ueff
Dear Wien2k users, I want to explain the negative temperature co-efficient of Co50Ga50 alloy using DFT. For this, I have run the SCF calculation using experimental XRD parameters with simple spin polarized case. Although, I have seen a sharp fall of DOS around the Ef in total DOS, there have been a few DOS available. Hence, to explain the semiconductor like nature of this alloy, I thought to apply Ueff procedure to create artificial gap around Ef. The Ueff was applied to the d-states of Co atom only as most of the states around the Ef are from the Co-d-bands. For a typical SCF calculation (ie, Ueff= 0 eV), the Co d-t2g forms he bonding states and Co d-eg forms the anti-bonding states around the fermi level. I was expected a formation of band gap as both d-t2g and d-eg states are separate due to application of Ueff. However, in this case, d-t2g states are only moved well below the fermi level while d-eg are not effected. As Fermi level crosses at d-eg states, no gap was seen even for Ueff = 5 eV. Please see the attached data for both Ueff values. My doubt is, why Ueff applies only on d-t2g and why not on both. If this is the case, how can I approach to move both d-t2g and d-eg states together. please give me some suggestions on this problem. thanks venkatesh Co50Ga50_Co_d_eg.pdf Description: Adobe PDF document Co50Ga50_Co_d_t2g.pdf Description: Adobe PDF document Co50Ga50_d_eg_Ueff=5eV.pdf Description: Adobe PDF document Co50Ga50_d_t2g_Ueff=5eV.pdf Description: Adobe PDF document ___ 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
