Hi. Question about describing O2 molecule with different charges.

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Chan-Woo Lee · #1 Post by **Chan-Woo Lee** » Wed Oct 04, 2006 7:17 pm

Hi.

I have a question about describing O2 molecule with different charges:O2_2-, O2_1-, and O2.

I saw a presentation about adsorption energy difference on surface with different charge states (peroxide and superoxide).

First question is "Is it possible to do that with DFT?" I thought that if we have extra charge, the charge would be smeard out.

Second question is if possible, what kind of tags do I have to add on INCAR?

Thanks in advance.

Chan-Woo

#2 Post by **admin** » Wed Oct 18, 2006 3:24 pm

even if you charge up your system (by setting NELECT to a different number than the total number of valence electrons) the charge may not stay localized at a certain atom (you can add/subtract electrons from the whole system only)
please mind that
--) periodic charged systems diverge (so it is only meaningful to charge clusters or molecules)
--) apply multipole corrections: please have a look at the "Monopole, Dipole and Quadrupole corrections" and the "Dipole corrections for defects in solids" chapters in the online handbook.