Really not surprising... I've performed some calculations on Co-phthalocyanine, that is, a Co(II) ion "dressed" by an organic molecule (odd number of electrons, S=1/2 on cobalt), in contact with a Pb surface (even number of electrons). A charge transfer of one electron from the Co atom to the Pb slab quenches the Co magnetic moment to S=0, as also measured by spin-polarized STM. As Heather and Jia say, it may be very important to know if some charge transfer process between your "undressed" (:-)) Co atom and your (metal?) slab takes place. It should depend on the relative positions of the Co electronic levels with respect to the metal Fermi energy (enough k points...?). You may check this also by using the pp.x code in order to subtract the Co and slab charge density to the total (Co+slab) charge density, thus obtaining an .xsf charge density plot you can look at with xcrysden. Beyond GGA methods (GGA+U on the 3d shell of Co?) may be also useful, if you are able to calculate/estimate a meaningful value for the Hubbard U. HTH. Without looking at your real system it is unlikely we can advice you more than this, I suppose...
Giuseppe Giuseppe Mattioli ISM-CNR Italy Quoting jia chen <jiachen at princeton.edu>: > Hi, > > If I understand you correctly, there is electron transfer between the > surface and the Co atom which makes the spin polarization of Co atom to be > 1. Not very surprising to me. > > On Mon, Aug 8, 2011 at 7:16 PM, Izaak Williamson <izaakw89 at yahoo.com> > wrote: > >> Thank you Heather and Jia for your replies. For a single Co atom, I do get >> the total magnetization of 3 but when Co is on a surface, its spin >> polarization comes out to be 2, which is S=1. The all-electron calculations >> were also done using pbe functional and on the same surface and with the >> same coverage of Co. >> >> Heather, what do you mean by locally? I do calculate the spin polarization >> from pdos. The whole system does have an even number of electrons but why >> does it result in S=1? Any explanation would be appreciated. >> >> >> -- >> Izaak Williamson >> Research Assistant >> Physics Department >> Boise State University >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- > Jia Chen >
