Clarify the DOS simulation

[manoj_wijesingha]

Hi Colleagues,
I could run the VASP simulation for DOS calculation of the Goethite surface (FeOOH). But it does not show the band gap on this DOS plot. However, it should have around 2.5 eV for the band gap. I found these papers (doi.org/10.1016/j.commatsci.2019.109110, doi.org/10.1021/acs.jpclett.4c02493, and doi.org10.3390ma15041465) and mentioned with the figures which show the bond gap of the Goethite. I have attached the files and the Images of the DOS plots of mine and others. Could please provide the and assist me to clarify this issue.
Thank you,

Best Regards,
Manoj.

[manoj_wijesingha]

Hi Colleagues,
Could you please consider these papers regarding the issue.
Thank you.

[jonathan_lahnsteiner2]

Dear manoj wijesingha,

I moved the topic to the users for users forum because the question is not really related to the usage of vasp. Here you can discuss with other users research related topics.

After briefly reviewing your input files and the computational section of the paper "Formation and Recombination Dynamics of Polarons in Goethite: A Time-Domain Ab Initio Study," which you sent, I believe the issue with your simulation is that you are using the standard PBE functional, whereas the paper uses PBE+U. This is specified in the "Simulation Details" section:

To accurately describe the localized behavior of Fe 3d orbitals, an on-site Coulomb correction (U = 6 eV, and J = 1 eV) was applied.

I recommend updating your simulation to use the PBE+U approach with the same U and J values as described in the paper. You will find more information about PBE+U on the following wiki pages:
https://www.vasp.at/wiki/index.php/NiO_GGA%2BU
https://www.vasp.at/wiki/index.php/LDAUTYPE
https://www.vasp.at/wiki/index.php/LDAU

All the best Jonathan

[manoj_wijesingha]

Hi Jonathan,
Sounds good, and I will let you know the updates. Thank you.

Best Regards,
Manoj.