[CP2K:10136] DFT+U calculation problems

[Xiaohui Yang]

Dear Matthias,

Many thanks for your reply! I will check the 3d occupations. As you 
mentioned, the result converged to different states for the same 
configuration, I am wondering if the SCF threshold is too large in this 
case. The previous EPS_SCF was 1.0E-7, I am going to try a smaller 
threshold for a more accurate result.

Thanks again for your help!

Best Regards,

Xiaohui

在 2018年4月1日星期日 UTC+8下午11:13:16，Matthias Krack写道：
>
> Dear Xiaohui
>
>  
>
> It seems the two DFT+U runs converged to different states for the same 
> atomic configuration, since band gaps and spin densities are quite 
> different. The Hubbard U term promotes an electron localisation, in your 
> case of the Ti 3d electrons. Different 3d orbital occupation patterns can 
> result in different total energies, especially for large U values. You can 
> check the 3d occupations by activating the &PLUS_U print section in 
> &FORCE_EVAL/&DFT/&PRINT.
>
>  
>
> Best regards
>
>  
>
> Matthias
>
>  
>
> *From:* cp... at googlegroups.com <javascript:> [mailto:
> cp... at googlegroups.com <javascript:>] *On Behalf Of *Xiaohui Yang
> *Sent:* 01 April 2018 14:24
> *To:* cp2k
> *Subject:* [CP2K:10136] DFT+U calculation problems
>
>  
>
> Dear, all
>
>  
>
> I did some calculations with DFT+U functional recently, they all obtained 
> from the CP2K program. 
>
>  
>
> At first, I calculated the geometry optimization of the structre, and 
> obtained the total energy directly from the last optimized structure (let's 
> say E1). Then, I ran a single point energy calculation with the same 
> optimized structure and got the total energy E2. 
>
>  
>
> However, those two total energies (E1 & E2) I collected from the exact 
> same structure have significant difference, E2-E1 = 1.2 eV.  
>
>  
>
> When checking their output results,  I find that the total energy 
> difference could be attributed to two parts, DFT+U energy and  Core 
> Hamiltonian energy. The input and output files are attached below. 
>
>  
>
> As far as I know, the total energy calculated from the same settings and 
> structures should be the same. I have no idea about these results. Could 
> you please help me check what is wrong with my calculation? Any comments 
> will be greatly appreciated. 
>
>  
>
> Best Regards,
>
>  
>
> Xiaohui
>
>  
>
>  
>
>  
>
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