Dear Yuvam,
> I wanted to know how do I know in what orbital how much U parameter I should > provide. You can compute U from first principles using the hp.x code which is a part of Quantum ESPRESSO. > 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. In QE there is a multichannel implementation for DFT+U, but it is still experimental. You can find some examples in q-e/test-suite/pw_lda+U. > Suppose I used U=5 in QE, how should I know what value should I use for > SIESTA? The value of U is not transferable from one code to another. U depends on many factors (Hubbard manifold, pseudopotentials, functional, etc.). Have a look here: http://theossrv1.epfl.ch/Main/DFTHubbard > If I use U=5 for 3d in SIESTA, what should I use for 4s as it is also one of > the outermost orbitals. Applying the U correction to s-type orbitals is questionable. Typically the U correction is applied to the orbitals of the d and f type. Sometimes people put U also on p-type orbitals, but there is also no general consensus about this. U=5 for 3d in SIESTA, does not mean that you will have U=5 for 3d in QE (see my comment above). Just compute it using hp.x. Greetings, Iurii -- Dr. Iurii TIMROV Postdoctoral Researcher STI - IMX - THEOS and NCCR - MARVEL Swiss Federal Institute of Technology Lausanne (EPFL) CH-1015 Lausanne, Switzerland +41 21 69 34 881 http://people.epfl.ch/265334 ________________________________ From: users <[email protected]> on behalf of Yuvam Bhateja <[email protected]> Sent: Thursday, October 29, 2020 1:58:44 PM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] DFT+U calculation and Hubbard_J0 parameter 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, <[email protected]<mailto:[email protected]>> wrote: Dear Yuvam please see below. Il giorno mer 28 ott 2020 alle ore 10:58 Yuvam Bhateja <[email protected]<mailto:[email protected]>> 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 _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu>) users mailing list [email protected]<mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users -- Matteo Cococcioni Department of Physics University of Pavia Via Bassi 6, I-27100 Pavia, Italy tel +39-0382-987485 e-mail [email protected]<mailto:[email protected]> _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu>) users mailing list [email protected]<mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users
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