[CP2K-user] DFT+U calculations for Cr3+ in MgCl2-KCl melts

[Xiaomei He]

Dear Slava,

Can I ask you a question? 
I want to applied DFT+U method too, but I don't kown how to measure 
U_MINUS_J value , I find in you case the value is only  0.1234777, So what 
dose 'J' mean and how to calculate?
Thank you very much.

Xiaomei 

在 2019年4月24日星期三 UTC-4下午12:22:27，Vyacheslav Bryantsev写道：
>
> Dear CP2K Group,
>
> There are a couple of ways to setup antiferromagnetic calculations for 6 
> Cr3+ ions (3d3 state) dissolved in MgCl2-KCl melt. 
>
> One way is to use MAGNETIZATION keyword. Another way is to use the BS 
> section (commented below)
>
> &KIND Cr1
>       ELEMENT Cr
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       POTENTIAL GTH-PBE-q14
>       *MAGNETIZATION 4.0*
>       &DFT_PLUS_U
>         L 2
>         U_MINUS_J 0.1234777
>         # U = 3.36 eV
>         U_RAMPING 0.01234777
>        &END DFT_PLUS_U
>  
>
>
>
>
>
>
>
>
>
> *!       &BS !        &ALPHA !         NEL +1 -1 !         L 2 0 !         
> N 3 4 !       &END ALPHA !       &BETA !        NEL -5 -1 !        L 2 0 ! 
>        N 3 4 !      &END BETA*
>      &END BS
>     &END KIND
>     &KIND Cr2
>       ELEMENT Cr
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       POTENTIAL GTH-PBE-q14
>       *MAGNETIZATION -4.0*
>       &DFT_PLUS_U
>         L 2
>         U_MINUS_J 0.1234777
>         # U = 3.36 eV
>         U_RAMPING 0.01234777
>        &END DFT_PLUS_U
>
>
>
>
>
>
>
>
>
>
> *!       &BS!        &ALPHA!         NEL -5 -1!         L 2 0!         N 3 
> 4!       &END ALPHA!       &BETA!        NEL +1 -1!        L 2 0!        N 
> 3 4!      &END BETA*
>     &END KIND
>
> The problem I have is that the total E from two setups (MAGNETIZATION and 
> BS) can be somewhat different:
> For example, the Etot of a system (mol fractions are shown) is lower when 
> setting up calculations using BS
> 50-MgCl2-50-KCl-5-CrCl3
> Etot = -8997.64290729994173 using BS section
> Etot = -8997.62650294793639 using MAGNETIZATION keyword
>
> However, for a different composition, the Etot is lower using 
> MAGNETIZATION 
> 15-MgCl2-85-KCl-5-CrCl3
> Etot = -6895.30145964661006 using BS section
> Etot = -6895.31001188029859 using MAGNETIZATION keyword
>
> The resulting spin moment on each Cr3+ in both cases are close to +3 and 
> -3, as expected.
>
>
> *What are the general recommendations to correctly find a ground 
> electronic state using DFT+U for transition metal ions in solution/melts?*
>
> *Are there any additional checks one can do to make sure the ground 
> electronic state is found?*
> After the ground electronic state is found, the next step will be to run 
> AIMD simulations. 
> The input and output files for these examples are given as attachments.
>
> Thank you,
> Slava
>
>
>
>
>
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