Sorry sir in the previous plot the energy difference was not per atom. So here I am attaching the Corrected plot. My system contains 20 atom.
On Wed, Jul 1, 2015 at 6:09 PM, paresh rout <[email protected]> wrote: > Thank you very much sir. That was a very helpful reply. Now I understand > smearing. Just one more query, I did a convergence test with k-point > sampling by fixing the F-D smearing value to 0.00184 and the energy > difference between C-type and G-type seems to be converged (I have > attached the convergent test plot). If I understand your explanation > correctly then this result should also be reliable. Please let me know if I > am wrong. > > I will also do the convergent test with M-V(0.01) and the second solution > that you have suggested. > (The K-points grids are 8 8 6 , 10 10 8, 12 12 10, 14 14 12, previously I > was using 8 8 6) > > Kind Regards > Paresh Chandra Rout > Research Scholar > INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH, BHOPAL > > > On Wed, Jul 1, 2015 at 12:56 PM, Nicola Marzari <[email protected]> > wrote: > >> >> >> Dear Paresh, >> >> >> maybe this is easier to follow: >> http://theossrv1.epfl.ch/Main/ElectronicTemperature >> >> The main concept is that with very small smearing you need *a lot* of >> k-points >> to perform the correct Brillouin zone integrations - so with a 0.00184 >> smearing >> you have a *large* error due to insufficient sampling, not a small error. >> >> Solution 1 - if you do not want to think, ever, in your life, use 0.01 >> Ry of m-v >> or m-v smearing, and increase the k-point sampling until the difference >> in energy >> between G and C type is converged. >> >> Solution 2 - plot the energy difference between G and C as a function of >> smearing, >> for m-v smearing of 0.005, 0.010, 0.015, 0.020, 0.025, and with at least >> 3 or >> 4 k-point sampling. Use the discussion from >> http://theossrv1.epfl.ch/Main/ElectronicTemperature >> to understand what to do. >> >> nicola >> >> >> >> On 30/06/2015 17:07, paresh rout wrote: >> > Dear all, >> > I am dealing with a transition metal oxide compound (ABO3), Where I use >> > cold smearing *m-v(0.02)* for geometry optimization and for total energy >> > calculation I use *f-d (0.00184*) at the final optimized structure. I >> > have calculated the total energy for various type of magnetic ordering >> > like (G-type, C-type). The total energy (SCF) for G-type and C-type are >> > in reverse ordering for different smearing technique (*G-type is the >> > ground state for* *MV smearing and C-type is the ground state for FD*). >> > But when I reduced the value of degauss of *MV to 0.008 *I got the same >> > ordering as FD. >> > I am very confused about the smearing technique . I have also read Prof. >> > Nicola's thesis about smearing but there I did not get rid of my >> > confusion also I did not find about FD technique . Can anybody kindly >> > tell me about the right smearing technique which I can use for the spin >> > polarized calculation ? Any reply would be highly appreciated. >> > >> > >> > Kind Regards >> > Paresh Chandra Rout >> > Research Scholar >> > INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH, BHOPAL >> > >> > >> > >> > _______________________________________________ >> > Pw_forum mailing list >> > [email protected] >> > http://pwscf.org/mailman/listinfo/pw_forum >> > >> >> -- >> >> ---------------------------------------------------------------------- >> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL >> Director, National Centre for Competence in Research NCCR MARVEL, EPFL >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> > >
Conv1.pdf
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