[QE-users] DFT+U calculation and Hubbard_J0 parameter

[Yuvam Bhateja]

Thank you very much for this valuable information.

I wanted to know how do I know in what orbital how much U parameter I
should provide.
In QE, there's only one option of Hubbard_U and not any orbital specific
data. But in other programs like SIESTA, I had to put U and J value for
each orbital, 3d and 4s in case of Cr.
Suppose I used U=5 in QE, how should I know what value should I use for
SIESTA?
If I use U=5 for 3d in SIESTA, what should I use for 4s as it is also one
of the outermost orbitals.

Regards
Yuvam


On Wed, 28 Oct 2020, 5:03 pm Matteo Cococcioni, <matteo.cococcioni at unipv.it>
wrote:

>
> Dear Yuvam
>
> please see below.
>
>
> Il giorno mer 28 ott 2020 alle ore 10:58 Yuvam Bhateja <yuvamb16 at gmail.com>
> ha scritto:
>
>> Hello experts,
>>
>> I have been using Quantum ESPRESSO for my project and now I wanted to
>> include DFT+U in my calculation.
>>
>> I was using lda_plus_u_kind = 0 (which only uses Hubbard_U parameter)
>> along with Hubbard_J0.
>> For example-
>>
>> lda_plus_u_kind=0
>> Hubbard_U(1)=5.0
>> Hubbard_J0(1)=0.48
>>
>> Using the above configuration my system converged perfectly.
>>
>> I wanted to know if I am doing something wrong here? Will the value of
>> Hubbard_J0 be even considered if I am using lda_plus_u_kind=0?
>>
>
>
> why do you think there is something wrong?
> In order to understand whether J0 makes any difference just try without it
> and compare the results.
>
>
>
>>
>> I wished to replicate the results in other softwares like SIESTA which
>> only uses rotationally invariant scheme (i.e., equivalent to lda_plus_u=1).
>> Can I use values of U=5.0 and J=0.48 as mentioned above in other DFT
>> codes?
>>
>
> strictly speaking they are not the same thing (unless J = J0 = 0). here is
> the reference for J0: PHYSICAL REVIEW B 84, 115108 (2011). But I don't know
> how similar the results would be.
>
> HTH
>
> Matteo
>
>
>
>
>>
>> Any suggestions would be very helpful.
>>
>> Regards
>> Yuvam Bhateja
>> _______________________________________________
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>
>
>
> --
> Matteo Cococcioni
> Department of Physics
> University of Pavia
> Via Bassi 6, I-27100 Pavia, Italy
> tel +39-0382-987485
> e-mail matteo.cococcioni at unipv.it <lucio.andreani at unipv.it>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
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