dear Lorenzo PaulattoThank you for you clear explanation i understood it now. previously i was not clear how these fractions are coming but now it is clear. Thank you very much for your explanation
On Sat, Sep 12, 2009 at 1:45 PM, Lorenzo Paulatto <paulatto at sissa.it> wrote: > > On Sat, September 12, 2009 08:15, udayagiri sai babu wrote: > > Dear all > > Can somebody clearly tell me how to define occupations from input. I > cant > > find much about that in this forum. The card "occupations" described in > > the > > example 11 for Al is not at all clear to me. What are those values mean. > > Looking forward to your help.... > > > It's quite easy, actually, there are only a couple of points you have to > keep in mind: > > 1. if nspin=1 occupations can go from 0 to 2, you have to specify the > occupation from the lower to the highest band and the sum of the > occupations will have to be the number of electrons; > > 2. if nspin=2 occupations go from 0 to 1, you specify the occupation for > spin up first, then for spin down (always on a newline); > > Let's say you want to reproduce the calculation of the Cr isolated atom, > with semicore states in valence: 3s2 3p6 4s1 3d5 4p0 > > first with nspin=1 and spherical (as it is done in ld1.x): > OCCUPATIONS > 2 2 2 2 1 1 1 1 1 1 0 0 0 > !3s2 3p6 4s1 3d5 4p0 > > then spin polarized (nspin=2), according to Hund's rule you have to > maximize the total angular momentum: > OCCUPATIONS > 1 1 1 1 1 1 1 1 1 1 0 0 0 > 1 1 1 1 0 0 0 0 0 0 0 0 0 > !3s2 3p6 4s1 3d5 4p0 > > Chrome is a lucky case, as it has a spherical ground state. As a last > example let's take an oxygen atom (2s2 2p4) and set the occupations to > reproduce the ld1.x calculation: > OCCUPATIONS > 2 4/3 4/3 4/3 > > or, equivalently: > OCCUPATIONS > 2 1.333333 1.333333 1.333334 > > > I hope it helps, best regards > > -- > Lorenzo Paulatto > SISSA & DEMOCRITOS (Trieste) > phone: +39 040 3787 511 > skype: paulatz > www: http://people.sissa.it/~paulatto/<http://people.sissa.it/%7Epaulatto/> > > > > ---------------------------------------------------------------- > SISSA Webmail https://webmail.sissa.it/ > Powered by SquirrelMail http://www.squirrelmail.org/ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- U.Saibabu PhD student, Deformation mechanisms modeling group, Materials engineering department, IISc Bangalore, India. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090912/f14a56e7/attachment.htm
