[Wien] Number of k points
No. This depends on the details of your reaction. The correct procedure is to use converged k-meshes, i.e. test each single calc. for k-convergence such that E-tot is changing less than your required accuracy. If your reaction is: metal + molecule -- insulator you need probably MANY k-points for the metal, 1 k-point for the molecule (in a big supercell) few k-points for the insulator. In addition, not the total number of k-points in the BZ is important, but its density in reciprocal space. I.e. if one of the reactants has only one atom/cell (and thus a very BIG reciprocal cell), but another reactant has a very big unitcell, you should consider this in your k-mesh and use a large and small number of k-points, respectively. The number of special k-points is NEVER really important, since this may change drastically with symmetry. Che Franklin N. schrieb: Dear fellow users, I am a new Wien user and I've got a very general question: I am calculating reaction enthalpies and I read somewhere that when calculating the energies of reactants and products, the number of k points should be the same for all of them in order to be comparable. Does this refer to the total number of k points in the BZ or the special k points generated? Thanks in advance for your help. Che Franklin N. Chem Graduate Student UNBF, Canada ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- P.Blaha -- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 Email: blaha at theochem.tuwien.ac.atWWW: http://info.tuwien.ac.at/theochem/ --
[Wien] valence-only calculations
In standard WIEN2k this is NOT possible. a) edit run_lapw (or whatever script you use) and comment the call to the program lcore. b) After init_lapw (before run_lapw) you've get a case.vsp file from lstart. run x lcore , which will produce a core density and case.scfc file coming from atomic potentials. c) be aware, that for all atoms on the left side of the periodic table, WIEN2k will calculate semicore states (eg. Li 1s, or Ti 3s,3p) self-consistently using local orbitals and they are not constraint. Except for analysis, one should NOT do a bad calculation and freeze the core. Abdullah Al-Sharif schrieb: Where can I control the orbitals which are not updated during scf cycles? I need to do valence-only calculations (i.e not allowing core charge to relax). ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- P.Blaha -- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 Email: blaha at theochem.tuwien.ac.atWWW: http://info.tuwien.ac.at/theochem/ --
[Wien] Crystal field splitting in empty 3d band of Fe2O3
Dear Y. Ding, For the material Fe2O3 having the formal high-spin Fe3+ and a closed up-spin shell, I think LDA (when giving an insulating solution) or LDA+U partial d-DOS can well show the t2g-eg (if being eigenorbitals) crystal field splitting. Just a note: have you worked with a hexagonal lattice coordinate or a local octahedral coordinate ? May the short Fe-Fe pair or a trigonal field distort too much the crystal field level diagram ? best regards -- H. Wu On Thursday 17 September 2009 07:51, Pavel Novak wrote: Dear Yang Ding, yesterday I forgot third point, which perhaps could give answer to your question. If U is chosen such that it put d-states close to the oxygen p- states, hybridization increases and it shifts the d-levels down if EdEp, or up if EdEp. Regards Pavel On Wed, 16 Sep 2009, Pavel Novak wrote: Dear Yang Ding, care is needed when estimating the crystal field splitting from the LDA+U calculation using the DOS. There are two reasons for it. First, the LDA+U lower the energy of more occupied states and increase the energy of less occupied states. Even if the bands are above Fermi energy, they contain nonzero fraction of electrons (cf :QTL in scf file), which is different for eg and t2g states, hence LDA+U distorts the splitting. Second, the selfinteraction of the d-electrons is present, again distorting the crystal field splitting. Regards Pavel Novak On Tue, 15 Sep 2009, Yang Ding wrote: Dear WIEN2k users, I am really new to WIEN2k, and wondering if you could give your advice and experience on following question concerning the crystal filed splitting calculated from WIEN2k. In order to understand if the pre-edge splitting appearing in the Fe K-edge spectra (1s-4p transition) measured by emission-XANES on Fe2O3 [Groot et al. J. Phys.: Condens. Matter 21 (2009) 104207 http://www.iop.org/EJ/abstract/0953-8984/21/10/104207/], is linked to crystal-filed splitting in 3d empty band. We did a very preliminary ground state calculation using WIEN2k based on GGA+U (and LSDA+U) with U = 4 eV structure to check the crystal field splitting in empty d band above Fermi level. As a result, we found that above 2-6 eV above Fermi level, the energy of t2g is higher than that of eg. This result is similar to what reported by Rollsman et al (PHYSICAL REVIEW B 69, 165107 (2004) http://prola.aps.org/abstract/PRB/v69/i16/e165107) on Fe2O3. In his calculation (GGA/LSDA+U , U= 4eV), the energy of t2g is also higher than that of eg. So my question is why the t2g and eg are reversed in DFT, but the Multiplet calculation gives contradictory results (i.e from Groot et al.). I noticed that Glatzel et al (PHYSICAL REVIEW B 77, 115133 (2008) http://prola.aps.org/abstract/PRB/v69/i16/e165107) reported that they obtained the right crystal field splitting using (LDA+U, U=6 eV) from WIEN2k. So we wonder if we might missed something in the calculations? Thanks in advance for your help,
[Wien] MAE
Dear users, ??? I am performing spin-orbit coupling calculations to calculate the magnetocrystalline anisotropy energy. So does it make sence to obtain two different number of k points after initialization for 001 and 100 dirction for the same k-mesh? Best regards Bothina -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20090917/2777897f/attachment.htm
[Wien] MAE
Dear users, ? let me make it clear. I want to calculate the MAE of a multilayer system of Fe/W I did complete spin polarized scf calculations for this system . I took the result of the well converged (of charge and forces)? and? ran initso script , for both 001 and 100 directions, but with the same input number of k points , I got diffrent k-list ( same k mesh), the question is why? and how can I unify this list to calculate the MAE ? Thanks Bothina? --- On Thu, 9/17/09, bothina hamad both_hamad at yahoo.com wrote: From: bothina hamad both_ha...@yahoo.com Subject: [Wien] MAE To: A Mailing list for WIEN2k users wien at zeus.theochem.tuwien.ac.at Date: Thursday, September 17, 2009, 6:37 PM Dear users, ??? I am performing spin-orbit coupling calculations to calculate the magnetocrystalline anisotropy energy. So does it make sence to obtain two different number of k points after initialization for 001 and 100 dirction for the same k-mesh? Best regards Bothina -Inline Attachment Follows- ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20090917/8cda3f87/attachment.htm
