[Pw_forum] about GGA+U calculation

[Prasenjit Ghosh]

Dear Bipul,

ZnO is tricky.......if you are interested in correct band gap opening and
positioning of the VBM and CBM, you need to apply U on both Zn and O. The
recommended values are 12 and 6.5 eV for Zn and O respectively (see  J. Am.
Chem. Soc. 2011, 133, 5893-5899). However, unlike other cases, these does
not have a physical significance.

Prasenjit

On 24 December 2014 at 10:41, Bipul Rakshit <bipulrr at gmail.com> wrote:

>
> Dear PWSCF users,
> I am doing GGA+U calculation for ZnO wurtzite structure. I attached the
> input file for the same.
> My doubt is for using "Hubbard U" we are using two additional tags
> (compared to simple GGA calculation)
>                lda_plus_u = .true.,
>               Hubbard_U(1) =8.0, Hubbard_U(2)=0.0,
>
> So I am applying Hubbard U=8 eV on my first species (i.e. Zn) and 0.0 eV
> on Oxygen.
> But how can I understand that this Hubbard U of 8 eV is applied on Zn- d
> states?
> or do I have to specify some additional tags or something?
>
> Kindly help in this matter.
>
> Thanks
> --
> Dr. Bipul Rakshit
> Research Associate,
> Institute of Physics (IOP),
> Bhubaneswar- 751 005
> Orissa
> India
>
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>



-- 
PRASENJIT GHOSH,
IISER Pune,
Dr. Homi Bhabha Road, Pashan
Pune, Maharashtra 411008, India

Phone: +91 (20) 2590 8203
Fax: +91 (20) 2589 9790
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