[Wien] [Wien2k Users] Spin orbit coupling of Atom with many nonequivalent positions
Hi Stefaan, Thanks for your reply. I did it for all allotropes for uranium (with lo+apw for all orbitals) Keeping Emax as 2.50 (as per your suggestions in the book you have posted in Wien2k website) I got the following values. Alpha-uranium ENE wo spin orbit: -112331.927 Ry ENE with spin orbit: -112332.767 Ry (with 1470 k-points) Gamma-U ENE wo spin orbit: -56165.956 Ry ENE with spin orbit: -56166.379 Ry (816 k-points) If Emax is changed to 5.0 for example (I ask this question from the mail on hcp Tb; the case.in1 had 5.0 as Emax), then should it really be done (for my case?). I thought ( with my limited experience in Wien2k; I may be wrong ) that number of k-points should be increased for a more accurate ENE value. Anyway, after sufficient number of k-points ENE will not increase that much. Why at all Emax has to be changed and when? Suddhasattwa -Original Message- From: wien-boun...@zeus.theochem.tuwien.ac.at [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Stefaan Cottenier Sent: Monday, February 01, 2010 1:35 PM To: A Mailing list for WIEN2k users Subject: Re: [Wien] [Wien2k Users] Spin orbit coupling of Atom with many nonequivalent positions Do this thought experiment: take a structure with, say, 5 different inequivalent positions for the same element, and then do something unphysical: replace on one of the positions only the element by the next element in the periodic table. Would that really matter? Well... Or do the following computer experiment: calculate hypothetical bcc-U with and without spin-orbit coupling, and see what the difference on the total energy is (this would also be a way to explore the effect of Emax on spin-orbit coupling -- cfr. one of your previous posts). Stefaan Consider an atom A (heavy element) with let us say, 5 different non equivalent atoms in the crystal lattice. During the spin orbit coupling initialization, we have to modify the case.inso file. In case we incorporate only 4 atoms for so coupling and leave one of the nonequivalent position, will it really matter in the SCF cycle for the calculation of ENE? ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
[Wien] cohesive energy of Zirconium
Dear Sir i didn't get the method how to calculate the atomic density with LAPW please give me some detail I am very new in this field. I tried it from last month. thanks -- Mayank kumar gupta
[Wien] Problem of HCP Tb (the third time)
Comments are pasted at the relevant places: After a regular GGA+SO scf, commamd line: *runsp -ec 0.0001 -cc 0.0001 -so -i 1000* then i got some results as follows: :ENE:-46876.608343 Ry :MMTOT: 11.92563 uB :MMI001: 5.81891 uB :MMINT: 0.28781 uB ** * I changed the case.indmc with '1 3' and x lapwdm -c -so -up, and I got the following result:* ** case.scfdmup * Spin-polarized + s-o calculation, M|| 0.000 0.000 1.000 Calculation of X, X=c*Xr(r)*Xls(l,s) Xr(r)= I Xls(l,s) = L(dzeta) c= 1.0 atom Lup dn total :XOP 1 3 0.00332 1.25294 1.25626 * This is the orbital moment with SO only, and it is 1.25294 uB, direction is down. *Here, I am confused: * *1 The orbital moment is still too small, it should be around 5 uB. I don't know why ?* This is to be expected. With GGA+SO, the f-electrons are not sufficiently localized. All f-orbitals of the minority spin are near E_fermi, are more or less equally populated, and this leads to a zero (or low) orbital moment. *2 In case.inst, the initial spin is up, I think the orbital moment should be in the same* *direction as spin. Or **how can the total moment be around 10 uB ??* For the second half of the lanthanide series, the orbital and spin moment have the same direction, indeed (Hund's third rule). *(3)*based on the GGA+SO scf, then i added the U parameter. case.inorb and case.indm were prepared as follows: *case.indm* Are you sure you need case.indm? Do grep lapw2 :log : if lapw2 has the -c option, then lapwdm needs it too (and then you need case.indmc). If an old case.indmc is around with different content, that might spoil your calculation. * -9. Emin cutoff energy 1 number of atoms for which density matrix is calculated 1 1 3 index of 1st atom, number of L's, L1 0 0 r-index, (l,s)index * *case.inorb * * 1 1 0 nmod, natorb, ipr PRATT 1.0BROYD/PRATT, mixing 1 1 3 iatom nlorb, lorb 1 nsic 0..AFM, 1..SIC, 2..HFM 0.50 0.00U J (Ry) Note: we recommend to use U_eff = U-J and J=0 * run a regular GGA+SO scf, commamd line: *runsp -ec 0.0001 -cc 0.0001 -so -orb -i 1000* then i got some results as follows: :ENE:-46876.47444 Ry :MMTOT: 13.45593 uB :MMI001: 6.25394 uB :MMINT: 0.94806 uB *:ORB001: 0.00439 uB * ** * After the three steps above, I found orbital moment in case.scf which is 0.00439 uB. comparing with the 1.25294 uB generated last step, why it's so small after plus U( Ueff = 0.5 Ry) ??* Impossible to tell with this information (but see hereafter, the dmat files). Apparently adding U leads to a redistribution of the electrons over the f-orbitals, with a zero orbital moment as a result. Then, I changed the last line of case.indmc from '0 0' to '1 3' after convergence, *case.indmc* * -9. Emin cutoff energy 1 number of atoms for which density matrix is calculated 1 1 3 index of 1st atom, number of L's, L1 1 3 r-index, (l,s)index * then I run *'x lapwdm -c -so -up'*, and I find the orbital moment in case.scfdmup is as follows: *case.scfdmup* * Spin-polarized + s-o calculation, M|| 0.000 0.000 1.000 Calculation of X, X=c*Xr(r)*Xls(l,s) Xr(r)= I Xls(l,s) = L(dzeta) c= 1.0 atom Lup dn total :XOP 1 3-0.00187 0.00626 0.00439 * * Orbital moment is 0.00439 uB, I was completely confused ??* This is just another way of calculating the number that is reported as :ORB in case.scf, hence you should find the same number, indeed. * *The following files are the dmatup/dmatdn files: ( I didn't get it) case.dmatup * 1 atom density matrix 3 0.00 0.00 -0.001873 L, Lx,Ly,Lz in global orthogonal system 0.99122776E+00 -0.11754944E-360.15671123E-12
[Wien] Problems of HCP (the fourth time)
Dear Dr. Stefaan: First, thank you very much for your helpful and enlightened reply, and your reply this time is very useful to me. I think there was a misunderstanding about my first question: case.scfdmup * Spin-polarized + s-o calculation, M|| 0.000 0.000 1.000 Calculation of X, X=c*Xr(r)*Xls(l,s) Xr(r)= I Xls(l,s) = L(dzeta) c= 1.0 atom Lup dn total :XOP 1 3 0.00332 1.25294 1.25626 * (1)My question is that why the direction of orbital moment is oppsite to the spin moment ? (spin moment is up, orbital moment is down, and I know the third rules of Hund's rules) (2)Is setting or changing the occupational numbers of electrons in case.dmatdn reasonable ? ( I mean we are try to simulate the microscopic behavior by First principles, we should not change or set any parameters in order to get the result we want.) I don't know why my understanding is right or not ,please correct it if I am wrong, thank you. (3)I checked the DOS by GGA or GGA+SO, the f_up states are always localized with or without plus U. So my understanding is that plus U can only redistribute the electrons of f_dn states, or localize the f_dn states electrons ? Am I right ? (4)I have read a book Condensed Matter Physics before, it said spin_orbit spliting energy is about 300 meV, so what the effect of SO on DOS ? Thank you very much, Stefaan. (Anyway, I will try to change the dmatup files and recalculate again first) Cheers. Your sincerely: Hui Wang -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100201/1aad52ae/attachment.htm
[Wien] Problems of HCP (the fourth time)
I think there was a misunderstanding about my first question: case.scfdmup * Spin-polarized + s-o calculation, M|| 0.000 0.000 1.000 Calculation of X, X=c*Xr(r)*Xls(l,s) Xr(r)= I Xls(l,s) = L(dzeta) c= 1.0 atom Lup dn total :XOP 1 3 0.00332 1.25294 1.25626 * (1)My question is that* why* the direction of orbital moment* is oppsite to* the spin moment ? (spin moment is up, orbital moment is down, and I know the third rules of Hund's rules) This file tells you that the orbital moment is +1.25626 (and not -1.25626), and that the dn-electrons are responsible for this orbital moment. That + means that it is parallel to the spin moment (which is positive as well). You probably confuse dn electrons with positive or negative moment. (2)Is setting or changing the occupational numbers of electrons in case.dmatdn reasonable ? ( I mean we are try to simulate the microscopic behavior by First principles, we should not change or set any parameters in order to get the result we want.) I don't know why my understanding is right or not ,please correct it if I am wrong, thank you. In an ideal world, you would get the correct answer, whatever your starting input is. We don't live in this ideal world, however. If you start from nonmagnetic atoms (by the case.inst file), you get a nonmagnetic result, even if your material is a ferromagnet. Similarly here, if you start from some specific distribution of electrons over the m-orbitals, you will end up in a particular result with one orbital moment. But no guarantee that no other starting distribution would lead to another solution with a different orbital moment and a lower total energy. This problem is already there for simple magnetic calculations, where you have some freedom how to distribute electrons over up and dn. With orbital potentials (where you have even much more freedom how to distribute electrons over many m-orbitals), it just gets worse. (3)I checked the DOS by GGA or GGA+SO, the f_up states are always localized with or without plus U. So my understanding is that plus U can only redistribute the electrons of f_dn states, or localize the f_dn states electrons ? Am I right ? Correct. The f-up shell is filled, well-localized, and therefore inert. All action happens in the dn-shell. (4)I have read a book Condensed Matter Physics before, it said spin_orbit spliting energy is about 300 meV, so what the effect of SO on DOS ? Schematically, it will split the single LDA-peak into two peaks, according to the relativistic quantum number kappa (you'll probably see that if you compare the f-dn DOS for GGA and GGA+SO). Adding U will introduce even more structure in the DOS. Stefaan
[Wien] [Wien2k Users] Spin orbit coupling of Atom with many nonequivalent positions
Do this thought experiment: take a structure with, say, 5 different inequivalent positions for the same element, and then do something unphysical: replace on one of the positions only the element by the next element in the periodic table. Would that really matter? Well... Or do the following computer experiment: calculate hypothetical bcc-U with and without spin-orbit coupling, and see what the difference on the total energy is (this would also be a way to explore the effect of Emax on spin-orbit coupling -- cfr. one of your previous posts). Stefaan Consider an atom A (heavy element) with let us say, 5 different non equivalent atoms in the crystal lattice. During the spin orbit coupling initialization, we have to modify the case.inso file. In case we incorporate only 4 atoms for so coupling and leave one of the nonequivalent position, will it really matter in the SCF cycle for the calculation of ENE?
