Stefano I did try with simple fermi-dirac (and very small broadening) and got the same result...The problematic case is nbnd=20 and not ndnd=12 or 25 cyrille
Stefano de Gironcoli wrote: >methfessel-paxton smearing is dangerous (because it is not >positive-defnite) when k-point sampling is not sufficient. > >When dealing with a "fake metal" as your molecule where the Fermi energy >should fall in gap of the spectrum I think it is more advisable to use >simple gaussian or marzari-vanderbilt smearing. The spurious negative >weights of m-p smearing the occupation of levels just above the Fermi >energy can lock some spourios state that shouldn't be there ... If you >have many kpoints this (in my experience... Nicola has a different >opinion) is never a problem. > >In any case the smearing contribution for a molecule should be zero >... which is not the case in your output ... particularly so for the >problematic cases with 12 or 25 bands.. > >TEST> grep -e TS -e ! Fe*.out >Fe_dimer_gamma_nbnd12.scf.out:! total energy = >-121.76376536 Ry >Fe_dimer_gamma_nbnd12.scf.out: smearing contrib. (-TS) = >-0.00157785 Ry >Fe_dimer_gamma_nbnd20.scf.out:! total energy = >-121.76907297 Ry >Fe_dimer_gamma_nbnd20.scf.out: smearing contrib. (-TS) = >0.00048313 Ry >Fe_dimer_gamma_nbnd25.scf.out:! total energy = >-121.76376546 Ry >Fe_dimer_gamma_nbnd25.scf.out: smearing contrib. (-TS) = >-0.00157856 Ry > >Does the problem (at least the one with 25 bands) disappears if you use >"m-v" of "gaussian" smearing ? >I would expect so... otherwise there is still something else. >hope it helps, >stefano > >Cyrille Barreteau wrote: > > >>Dear Paolo, >> >>Maybe I found the second exception due to another very special >>phase of the moon:-) What do I win in this case:-) >> >>You will find at the following links: >>the input file, the pseudo file and the three output >>corresponding to nbnd=12,20,25 respectively. >> >>http://www-drecam.cea.fr/spcsi/cbarreteau/tempo/Fe_dimer.scf.in >>http://www-drecam.cea.fr/spcsi/cbarreteau/tempo/Fe.pw91.vdb.UPF >>http://www-drecam.cea.fr/spcsi/cbarreteau/tempo/Fe_dimer_gamma_nbnd12.scf.out >>http://www-drecam.cea.fr/spcsi/cbarreteau/tempo/Fe_dimer_gamma_nbnd20.scf.out >>http://www-drecam.cea.fr/spcsi/cbarreteau/tempo/Fe_dimer_gamma_nbnd25.scf.out >> >>thanks for having a look at this case. >> >> cyrille >> >>- >>================================================================== >>Cyrille Barreteau | phone : +33 (0)1 69 08 29 51 >>CEA Saclay | fax : +33 (0)1 69 08 84 46 >>DSM/DRECAM/SPCSI | email cyrille.barreteau at cea.fr >>Batiment 462 | >>91191 Gif sur Yvette Cedex FRANCE >> ~~~~~~~~~~~~~~~~~~~~~~~~ >>http://www-drecam.cea.fr/spcsi/index.php >>http://www-drecam.cea.fr/Images/Pisp/cbarreteau/cbarreteau_fr.html >>http://www-drecam.cea.fr/Phocea/Membres/Cours/index.php >>================================================================== >> >> >> >> >>Paolo Giannozzi wrote: >> >> >> >> >>>On Nov 20, 2007, at 15:55 , Cyrille Barreteau wrote: >>> >>> >>> >>> >>> >>> >>>>Does anyone has experience about the behaviour >>>>of the various diagonalization schemes? >>>>Which one is better, in which case? >>>> >>>> >>>> >>>> >>>> >>>the so-called conjugate-gradient diagonalization basically >>>never fails; it uses less memory but it is much slower than >>>the block Davidson algorithm. The latter is also quite >>>robust but there is a tiny probability to end up in the wrong >>>ground state. The only such case I know happens in some >>>high-symmetry perovskites, if you start from superposition >>>of atomic states, with occupied states only, and if the phase >>>of the moon is close to 42. The problem disappears if you >>>add a few more states, or if you start from random wavefunctions. >>>I am quite surprised to hear that there is a case in which >>>you get good results with 12 states and bad with 20. >>>I wouldn't be surprised by the opposite. Could you please >>>post one jobs showing the problem? >>> >>>Paolo >>>--- >>>Paolo Giannozzi, Dept of Physics, University of Udine >>>via delle Scienze 208, 33100 Udine, Italy >>>Phone +39-0432-558216, fax +39-0432-558222 >>> >>> >>> >>>_______________________________________________ >>>Pw_forum mailing list >>>Pw_forum at pwscf.org >>>http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >>> >>> >>> >>- >> >>_______________________________________________ >>Pw_forum mailing list >>Pw_forum at pwscf.org >>http://www.democritos.it/mailman/listinfo/pw_forum >> >> >> > >_______________________________________________ >Pw_forum mailing list >Pw_forum at pwscf.org >http://www.democritos.it/mailman/listinfo/pw_forum > > -- ================================================================== Cyrille Barreteau | phone : +33 (0)1 69 08 29 51 CEA Saclay | fax : +33 (0)1 69 08 84 46 DSM/DRECAM/SPCSI | email cyrille.barreteau at cea.fr Batiment 462 | 91191 Gif sur Yvette Cedex FRANCE ~~~~~~~~~~~~~~~~~~~~~~~~ http://www-drecam.cea.fr/spcsi/index.php http://www-drecam.cea.fr/Images/Pisp/cbarreteau/cbarreteau_fr.html http://www-drecam.cea.fr/Phocea/Membres/Cours/index.php ==================================================================
