MAGMOM and GGA+U for Fe adsorption on SiO2 surface Si vancancy?

[fegg7502]

Dear all,

I want to calculate the adsorption of single Fe atom on SiO2 surface Si vancancy,.

I have two problems unclear till now.

First, I set ISPIN= 2, in the INCAR,. however, when I checked the dipole correction, it is found the energy change is about 2eV. I guess this difference is due to the 'magmom' tag.
my question is that is it necessary to set the 'MAGMOM' in the INCAR for this Fe atom, and why? if it were necessary, how to get this number?


Second, for the transition metal, I want to use the 'GGA+U', Could anyone tell me how to set the number for U if there is no experiment data at hand,


Thank you very much!

Best regards

[boris]

Hi
For the DFT+U calculation, if there's no experimental value for the U parameter, you can perform several calculations with different U and then find some data to compare with experiments (electronic structure, structural parameters, magnetism, etc.)

Regards.