Dear all,

I found a strange thing when I include spin-orbit coupling (SOC) in G0W0 calculations. The HF correction without SOC opens a large band gap comparing with GGA-PBE, however after including SOC, the HF gives a negative band gap as follows shown.

without SOC @ Gamma k-point:

<159|HF|159> = -11.62607 0.1017E-8 <159|DFT|159> = -10.84202 0.000000

<160|HF|160> = -10.28354 -.3978E-8 <160|DFT|160> = -10.42272 0.000000 HOMO

<161|HF|161> = -5.809332 0.262E-09 <161|DFT|161> = -8.814879 0.000000 LUMO

<162|HF|162> = -5.856881 -.242E-09 <162|DFT|162> = -8.845275 0.000000

with SOC @ Gamma:

<319|HF|319> = -7.648899 -.4403E-8 <319|DFT|319> = -9.515832 -.1267E-7

<320|HF|320> = -7.648894 -.1449E-8 <320|DFT|320> = -9.515823 0.000000 HOMO

<321|HF|321> = -9.057126 0.540E-09 <321|DFT|321> = -10.81462 0.6336E-8 LUMO

<322|HF|322> = -9.057129 0.2195E-8 <322|DFT|322> = -10.81461 0.000000

And the final G0W0 with SOC are:

B=319 Eo= -0.08 E= 1.32 E-Eo= 1.41 Z=0.81 nlXC=-7.648899 lXC=-9.515832 So=-0.129964

B=320 Eo= -0.08 E= 1.32 E-Eo= 1.41 Z=0.81 nlXC=-7.648894 lXC=-9.515823 So=-0.132115

B=321 Eo= 0.08 E= 1.56 E-Eo= 1.48 Z=0.82 nlXC= -9.05713 lXC=-10.81462 So= 0.04808

B=322 Eo= 0.08 E= 1.56 E-Eo= 1.48 Z=0.82 nlXC= -9.05713 lXC=-10.81461 So= 0.05031

The G0W0 gives a similar band gap to PBE because of negative HF corrections? I also checked other k-points, the HF opens positive gaps between band 320 and 321. Considering some parameters are important to G0W0, I have tried several calculations with different GbndRnge and NGsBlkXp, however, G0W0 still around 0.2 eV, which is significantly smaller than the experimental value of about 1.2 eV. So, Is there something wrong with my calculations or Yambo can not perform G0W0 with SOC?

P.s. This is a perovskitic structure (ASnX3). The PBE band gap is 0.28 eV; PBE-SOC band gap is 0.16 eV. The pwscf generated band gap is compatible with other DFT codes.

The attachments are the main output of calculations with/without SOC by YAMBO.