Dear Nicola, with regards to your comments "it keeps you company during the voyage, > but shouldn't share your bed...", does this mean that smearing contribution print as "-TS" should be less than convergence criteria (typically 1mry) with regards to increase in no. of K points and KE cut-off for a SCF calculation? I would appreciate a clarification with best regards saqib javaid University of strasbourg.
Selon Nicola Marzari <nicola.marzari at materials.ox.ac.uk>: > > > Dear Giovanni, Cyrille, > > > the iron dimer has a very complex electronic structure (see e.g. our > PRL 2006 Kulik et al) - different multiplets, and for each multiplet, > different symmetries. > > In principle, there is no way to guess to which of the many > self-consistent states you'll converge to, and I suppose that what > you have here is that you have converged to different states. > You'll need to look at the total energy, kohn-sham eigenstates, and the > symmetry of those to understand what you are looking at > (also, there is no point in having more bands than efermi + 3*degauss - > empty bands above that threshold are useless). > > There is no easy way to force the code into one state or the other - > you could try using GGA+U - some U's will stabilize reliably one state, > and then by reducing smoothly the U (or increasing it) you might be able > to have (as a function of U) the energy of your preferred electronic > configuration. > > Last - for a cluster or a molecule smearing is used, somewhat > inappropriately, to help a calculation converge when using > iterative approaches - it keeps you company during the voyage, > but shouldn't share your bed (the real reason d'etre for > smearing is to improve k-point integrations in metals). > > nicola > > > On 2/15/11 5:42 PM, Giovani Faccin wrote: > > Dear Cyrille, > > > > I recalculated the dimer with different values of nbnd. Now some > > interesting changes appeared: > > > > Value of nbnd | Magnetization > > > > 10 4.00 > > 12 6.88 > > 14 6.49 > > 16 6.49 > > 18 6.49 > > 20 6.49 > > 22 6.88 > > 24 6.88 > > 26 6.49 > > 28 6.49 > > > > > -- > ---------------------------------------------------------------------- > Prof Nicola Marzari Department of Materials University of Oxford > Chair of Materials Modelling Director, Materials Modelling Laboratory > nicola.marzari at materials.ox.ac.uk http://mml.materials.ox.ac.uk/NM > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.
