Author Topic: spin polarization calculation on GNR  (Read 3509 times)

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Offline jerry

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spin polarization calculation on GNR
« on: December 26, 2011, 12:40 »
Dear,
    Recently, i followed the manual to do some calculation on GNR. zGNRs have different electronic structures which are dependent on the consideration of electron polarization. But, when i use different different user spin values, the bandstructure are also different. Why does this happen? Given the fact that the spin value of each atom will change to the optimal value during calculation.
   
    Thanks a lot!
                                             Jerry

Offline Anders Blom

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Re: spin polarization calculation on GNR
« Reply #1 on: December 26, 2011, 13:34 »
Without more information (like, magnitude of difference, and which initial states considered) it's hard to say anything specific, but there is at least the possibility that you end up in either the ferromagnetic or anti-ferromagnetic states (basically, if your edges have the same or opposite signs of the initial polarizations). Typically the anti-ferromagnetic state has a lower total energy and is thus the true ground state, but you can't reach the anti-ferromagnetic state from the ferromagnetic state without crossing an energy barrier, so if your initial configuration is ferromagnetic, you will converge to such a state, and find the correct lowest energy within the ferromagnetic subspace.

Offline jerry

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Re: spin polarization calculation on GNR
« Reply #2 on: December 26, 2011, 14:02 »
Dear Blom:
    I think you are absolutely right!

Thank you very much! :)