[QE-users] 回复: Is it acceptable to neglect spin, magnetism and U for CPMD simulation of iron oxides (Fe2O3, Fe3O4 and FeO)

[likejiang at ustb.edu.cn]

Thanks a lot for sharing this good paper, Nicola.

I will read this paper and use dft+hubbard in the future calculation for iron and its oxide.

All the best,
Kejiang

-----邮件原件-----
发件人: users-bounces at lists.quantum-espresso.org <users-bounces at lists.quantum-espresso.org> 代表 Nicola Marzari via users
发送时间: 2022年4月7日 18:58
收件人: users at lists.quantum-espresso.org
主题: Re: [QE-users] Is it acceptable to neglect spin, magnetism and U for CPMD simulation of iron oxides (Fe2O3, Fe3O4 and FeO)


Thanks Giuseppe,


couldn't agree more! Never being one to miss an opportunity to promote 
dft+hubbard, I would also add that these functional can be also more
accurate, because they screen a fock-like term with awareness of the local bonding - see Iurii's just-out work on batteries:
https://arxiv.org/abs/2203.15732

			nicola

On 07/04/2022 12:39, Giuseppe Mattioli wrote:
> 
> Dear Kejiang
> 
> Only EXX functionals such as PBE0 or HSE significantly increase the 
> computation time. DFT+U has been primarily developed as a 
> cost-effective method to correct delocalization errors in the case of 
> localized shells such as those present in transition metal oxides. 
> There are tons of literature on this... In my opinion (and I've 
> investigated several similar system with the same purpose) you cannot 
> neglect U, spin&co if you want to obtain meaningful (i.e., 
> publishable...) results. cp.x can manage open shell systems with a 
> fixed magnetic moment within the DFT+U framework. But you must 
> carefully setup and test your calculations, which are a bit on the "nonstandard" side.
> HTH
> Giuseppe
> 
> Quoting likejiang at ustb.edu.cn:
> 
>> Dear QE-Users,
>>
>> I am planning to do some CPMD simulation about iron oxides (Fe2O3,
>> Fe3O4 and
>> FeO) and their reactions with hydrogen at high temperature using cp.x 
>> of QE 7.0.
>>
>> As it is well known that spin and magnetism are the most fundamental 
>> characteristics for iron and its oxides, we should consider them 
>> (spin and
>> magnetism) and add U in many cases for 'scf' or 'relax'/'vc-relax'
>> calculations with pw.x.  But it seems that considering spin, 
>> magnetism and U will make things more complicated and significantly 
>> increase the computation time, I am wondering whether it is 
>> acceptable to neglect spin, magnetism and U for CPMD simulation of 
>> iron oxides (Fe2O3, Fe3O4 and FeO) and their reactions with Hydrogen 
>> gas. My goal is only to try to simulation the reduction process in 
>> atomistic scale, and the CPMD trajectory results are sufficient to 
>> capture the reduction mechanism while the accuracy of band gap, 
>> magnetism is not the focus of my study.
>>
>> Any comments or suggestions will be much appreciated.
>>
>> Thanks,
>> Kejiang
>>
>> -------------------------------------------------
>> Dr. Kejiang Li
>> School of Metallurgical and Ecological Engineering, University of 
>> Science and Technology Beijing Xueyuan Rd., Haidian District, Beijing 
>> 100083, P. R. China https://kejiangli.com/
> 
> 
> 
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA Via Salaria Km 29,300 - C.P. 
> 10
> I-00015 - Monterotondo Scalo (RM)
> Mob (*preferred*) +39 373 7305625
> Tel + 39 06 90672342 - Fax +39 06 90672316
> E-mail: <giuseppe.mattioli at ism.cnr.it>
> 
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--
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL Director, National Centre for Competence in Research NCCR MARVEL, SNSF Head, Laboratory for Materials Simulations, Paul Scherrer Institut Contact info and websites at http://theossrv1.epfl.ch/Main/Contact
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users at lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users