Dear Gavin I am highly thankful for the detailed reply. It is quite helping.
True Regards M. Sajjad On Wed, Aug 5, 2015 at 3:35 AM, Gavin Abo <gs...@crimson.ua.edu> wrote: > I don't know everything about DFT+U+SO calculations, but I will try to > answer your questions. See below. > > Dear users I am intended to perform FM+U+SOC calculation for Ca2CoSiO7. > The step that I understood to perform for such calculations are: > 1. run simple SCF with LDA using spin polarized calculations > 2. save and run initso_lapw > it asks about magnetization direction, Emax value, add RLO for NONE/ ALL/ > CHOOSE elements, spin-polarized case, selection of new structure for SO, > Number of kpoints. > 3. Import .inorb and .indm from SRC_templates for LDA+U calculation and > edit them by requirement. > 4. Finally use command runsp_lapw -p -so -orb -cc 0.0001 -ec 0.0001 -NI. > > My queries are: > a. Is it the right approach for the mentioned calculation? > > > Yes, the approach that you mentioned above looks fine. > > b. In second step, can we change magnetization direction? > > > If step 1 came before it, then you can 'set' the magnetization direction > in step 2. If you just completed step 4 and are going to back to step 2, I > think you need to do a save then a restore (i.e., restore_lapw) of the step > 1 calculation before you should 'change' the magnetization direction using > initso_lapw. > > how much Emax should be increased (default value is 5 Ry)? > > > You should be able to increase it until the output parameter you are > interested in has converged (i.e., do a convergence test with Emax) [ > https://email@example.com/msg02113.html > ]. > > Which option is correct for adding RLO? > > > If you don't know when to add them, enter N for NONE for RLO: > > > https://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg08381.html > > https://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg05958.html > > https://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg11478.html > > As it says in the Wien2k 14.2 usersguide on page 120 [ > http://www.wien2k.at/reg_user/textbooks/usersguide.pdf ], RLOs are used > for elements with semicore p-states: > > *We also provide an additional basisfunction, namely a ”relativistic-LO” > (RLO) with a* > *p1/2 radial wavefunction, which improves the basis and removes to a large > degree the dependency* > *of the results on EMAX and RMT (see Kuneˇs et al. 2001). It is particular > **helpfull for heavier atoms* > *with semicore p-states**, but it must not be used for EFG calculations.* > > Ca, Co, Si, and O should be relatively 'light' elements in the periodic > table [ https://en.wikipedia.org/wiki/Chemical_element#Atomic_numbers ]. > > do we need to increase kpoints (before it was 200 for simple scf)? > > > In the WIEN2k 14.2 usersguide (section 4.5.5 Spin-orbit interaction), it > mentions that SO can reduce the symmetry depending on how the direction of > magnetization is chosen. > > In the "Notes about spin-orbit (pdf)" file > (novak_lecture_on_spinorbit.pdf) at > http://www.wien2k.at/reg_user/textbooks/ (section 4.4), it mentions that > the reduction in symmetry has the consequence that the irreducible wedge of > the Brillouin zone must be enlarged. So generally yes, the number of > k-points need to be increased for the SO calculation. > > How much should you increase the k-points? You should able to determine > how many from a convergence test with k-points [ > https://www.beilstein-journals.org/bjnano/content/supplementary/2190-4286-2-45-S1.pdf > ]. > > c. Is there any way (like in mBJ we run init_mbj_lapw that imports > inm_vresp files and makes changes) to import .inorb and .indm file by > command line? > > > No, I'm not aware of a script like init_mbj_lapw for SO calculations. > > You could do programming of your own script to cp and/or edit .inorb and > indm files. I put such an example script called init_orb_lapw on my github > page [ https://github.com/gsabo/WIEN2k-Patches/tree/master/14.2 ] (click > WIEN2k-Patches and Download ZIP). You may try or modify init_orb_lapw at > your own risk (it should give some automation to what you have described > for step 3). > > d. Is the final command correct? > > > Yes, the step 4 command looks correct. However, removing the -NI in step 4 > might even help you catch a problem; for example, I think if you forget to > do a save_lapw, it will indicate that the broyd files exist from a previous > calculation and give you a few seconds before it automatically removes and > continues with the new calculation. Whereas with -NI, it might continue > with previous broyd files and possibly crash the calculation. > > and if someone wants to use GGA+U then simply it is required to run simple > SCF by GGA and then apply U or any other method? > > > Yes, you can simply run the SCF with GGA selected in case.in0 and then > apply U. For example, you could probably even do that between steps 1 and > 2: > > 1a. save -d LDAwithoutSO > 1b. Select GGA in case.in0 > 1c. runsp_lapw > 1d. save -d GGAwithoutSO > 1e. Create .inorb and .indm > 1f. runsp_lapw -orb > 1g. save -d GGAUwithoutSO > 1h. Select LDA in case.in0 > > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: > http://firstname.lastname@example.org/index.html > > -- Kind Regards Muhammad Sajjad Post Doctoral Fellow KAUST, KSA.
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