[QE-developers] DFT+U+SOC band structure

[Ignacio Alliati]

Dear QE developers,

I’m using PWSCF v.6.5 to address the effect of SOC in the band structure of bulk MnPS3. I’m comparing 4 runs, namely

Fig1_GGA.pdf: PBEsol without U
Run1 (Orange curve): Ncl without SOC
Run2 (Blue curve): Ncl with SOC

Fig2_GGA+U.pdf: PBEsol with U=2.7 eV
Run3 (Orange curve): Ncl without SOC
Run4 (Blue curve): Ncl with SOC

Run1 and Run2 (GGA) show a small impact of SOC, as expected. However, Run3 and Run4 (GGA+U) show a huge impact of SOC. Do you think this is physical?

I tend to think it is not, and that Run4 is not being shifted as expected by the Hubbard correction. I believe the reason may have to do with the following.

In Run3:
[Run3]$ grep 'Hub. E' stdoutscf | tail -n 1
Hub. E (dc, noflip, flip, total)    5.0002   5.0996  -0.0000   0.0994
[Run3]$ grep 'Hub. E' stdoutnscf
Hub. E (dc, noflip, flip, total)    5.0002   5.0996  -0.0000   0.0994

But in Run4:
[Run4]$ grep 'Hub. E' stdoutscf | tail -n 1
Hub. E (dc, noflip, flip, total)    5.0003   5.0999  -0.0002   0.0995
[Run4]$ grep 'Hub. E' stdoutnscf
Hub. E (dc, noflip, flip, total)    0.0000   0.0000   0.0000   0.0000

Also, in Run4, with a different number of cores, I get NaN instead of 0.000 when reading the Hubbard data. Do you know what may be causing this?

Thanks in advance,
Ignacio Martin Alliati
-----------------------------
PhD student
Maths and Physics
Queen’s University Belfast.

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