[Pw_forum] Hubbard for oxygen

[Giuseppe Mattioli]

Dear Youssef
You did not search well...:-)

ZnO
http://pubs.acs.org/doi/abs/10.1021/jp303781v
http://onlinelibrary.wiley.com/doi/10.1002/aenm.201301694/abstract

TiO2
http://pubs.acs.org/doi/abs/10.1021/jp1041316
http://pubs.acs.org/doi/abs/10.1021/jp509830w

Co-oxo, Ni-oxo
http://pubs.acs.org/doi/abs/10.1021/ja401797v
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.100.167206

and the very recent U-based hybrid functional ACBN0, applied to Zn,  
Ti, Fe and Mn oxides
https://journals.aps.org/prx/abstract/10.1103/PhysRevX.5.011006

> Finally I would like to discuss the effect of hybridisation on U,
> especially with mixed compounds where the oxygen electrons are shared on
> between both Hubbard and non Hubbard atoms, from my experience on double
> pervoskite the calculated value of U on Hubbard atoms including oxygen
> using the linear response approach by cococcioni et al  overestimate the
> band gap .

True! you should use a semiempirically fitted value (see the papers above).
HTH

Giuseppe

Giuseppe Mattioli
ISM-CNR
Italy

Quoting Youssef Aharbil <aharbil at gmail.com>:

> Dear Quantum espresso community,
>
> It's well known that adapting the Hubbard model in DFT give a better
> insight for the electronic structure on correlated materials, here the
> systems with d and f shell localisation are corrected by applying a U
> potential, but I don't understand why do we apply U also for oxygen,
> unfortunately I can't find any reference (may be my research wasn't so
> deep) giving more explanation.
>
> Finally I would like to discuss the effect of hybridisation on U,
> especially with mixed compounds where the oxygen electrons are shared on
> between both Hubbard and non Hubbard atoms, from my experience on double
> pervoskite the calculated value of U on Hubbard atoms including oxygen
> using the linear response approach by cococcioni et al  overestimate the
> band gap .
>
>> From my point of view I think that the value of U must be proportional to
> the number of electron only shared between Hubbard atoms and the oxygen.
>
> Thanks in advance.
>
> Youssef Aharbil
> Faculty of sciencs ben msik.
> Morocco


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    Giuseppe Mattioli
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