Yambo Community Forum

Posted: **Sun Feb 08, 2026 9:28 am**

Dear all,
When I was running a G1W0 calculation, I copied into the G1W0 directory all the files generated during my G0W0 run (ndb.HF_and_locXC, ndb.dipoles, ndb.pp*, ndb.cutoff, ndb.RIM, ndb.RIM_W). In the G1W0 input, I used the parameter `GfnQPdb` to read the quasiparticle energies produced by the G0W0 calculation, i.e., `GfnQPdb = "E < ./360b_15Ry/ndb.QP"`.
However, the results I obtained are very strange: compared with G0W0, the G1W0 result not only fails to open the band gap, but instead closes it.
I would like to know whether this is due to an operational mistake in my self-consistent evGW0 procedure, or because the number of bands stored in `ndb.QP` from G0W0 and used for G1W0 is too small (only a dozen or so bands around the Fermi level, though this is sufficient for BSE calculations).
Below I attach the G1W0 input file and the corresponding .r file. Thank you in advance for your help!

testg1w0_ppa_360b_15Ry.in.txt

r-testg1w0_360b_15Ry_HF_and_locXC_gw0_dyson_rim_cut_rim_w_em1d_ppa_el_el_corr.txt

Posted: **Sun Feb 08, 2026 4:37 pm**

Dear Xiangjun,

indeed, the results are strange.
But, I see nothing wrong in your input file. About your procedure, please see here a tutorial on the procedure:
https://wiki.yambo-code.eu/wiki/index.p ... alues_only

e.g. I would let the dipoles to be recalculated with the updated energies, but this should be a very minor issue.
Please note, your system starting point is a metal, but after the first iteration the gap open and yambo seems to take into account correctly of the new occupation numbers (see report Energies & Occupations section before and after reading the database). Anyway, is your system hexagonal Bi monolayer? If so, I think also the DFT band structure should have a gap (very small!). Because of that I would also let the HF part of the self energy to be recalculated with the new occupation numbers.

What is instead quite surprising and suspicious, is the execution time for your calculation. Your system it is not particularly large, and the execution times are extremely large. You should probably check if there is something odd in the compilation.

My suggestion is to check your compilation, compile the code in single precision, and repeat the procedure as indicated in the tutorial (avoiding recompiling the screening) and eventually check the role of QPkrange. For these checks I would also remove the spin-orbit coupling to make the calculation more handy.

Best,

Daniele

Posted: **Mon Feb 09, 2026 3:10 pm**

Daniele Varsano wrote: Sun Feb 08, 2026 4:37 pm Dear Xiangjun,

indeed, the results are strange.
But, I see nothing wrong in your input file. About your procedure, please see here a tutorial on the procedure:
https://wiki.yambo-code.eu/wiki/index.p ... alues_only

e.g. I would let the dipoles to be recalculated with the updated energies, but this should be a very minor issue.
Please note, your system starting point is a metal, but after the first iteration the gap open and yambo seems to take into account correctly of the new occupation numbers (see report Energies & Occupations section before and after reading the database). Anyway, is your system hexagonal Bi monolayer? If so, I think also the DFT band structure should have a gap (very small!). Because of that I would also let the HF part of the self energy to be recalculated with the new occupation numbers.

What is instead quite surprising and suspicious, is the execution time for your calculation. Your system it is not particularly large, and the execution times are extremely large. You should probably check if there is something odd in the compilation.

My suggestion is to check your compilation, compile the code in single precision, and repeat the procedure as indicated in the tutorial (avoiding recompiling the screening) and eventually check the role of QPkrange. For these checks I would also remove the spin-orbit coupling to make the calculation more handy.

Best,

Daniele

Dear Daniele,
Thanks for your help!!!

How can I install a single-precision build of Yambo 5.3?

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