GW correction is NaN
Posted: Fri Sep 17, 2021 12:12 pm
Dear developers,
I am calculating GW bands and doing convergence test on NGsBlkXp and BndsRnXp, while GbndRnge is keeped as 50. When I further increased NGsBlkXp from 15 Ry to 20 Ry and keep other settings unchanged, I encountered the problem, NaN GW correction and its self-energy:
# K-point Band Eo [eV] E-Eo [eV] Sc|Eo [eV]
#
19 4 -2.362984 NaN NaN
19 5 1.688877 NaN NaN
What is usually the resaon for this issue? I attach the corresponding report file.
I have also several questions related to GW calculations and it will be great if you can provide any advice.
1) In NSCF calculations of PWSCF, nbnd is set to be large like 1000, there are a few eigenvalues not fully converged. Will this be important and affect the GW calculations a lot? What can I do to solve this?
2) When I truncate Coulomb potential as a typical 2D material in Yambo, I find the calculated E_xc (-8.575967 Ry) by Yambo is not exact the same as the one in PWSCF (-8.57667827 Ry). They can be the same if I don't adopt the truncated c potential and RIM for integrals. Will this small difference affect the subsequent calculations in Yambo? Should I use assume_isolated='2D' to truncate Coulomb interaction in PWSCF as well?
3) What is the good signature of a converged GW correction? Should the variation of GW correction for the top VB and bottom CB be small than 0.01 eV? How is the accuracy of GW correction? I want a accurate GW bands not only the band gap.
4) Is it safe to always keep GDamping and dScStep default for a GW calculation?
5) Is it recommended to use Yambo 4.3 version? Someone told me Yambo 4.3 is more stable than Yambo 5.0.3.
Thanks a lot,
Changpeng
I am calculating GW bands and doing convergence test on NGsBlkXp and BndsRnXp, while GbndRnge is keeped as 50. When I further increased NGsBlkXp from 15 Ry to 20 Ry and keep other settings unchanged, I encountered the problem, NaN GW correction and its self-energy:
# K-point Band Eo [eV] E-Eo [eV] Sc|Eo [eV]
#
19 4 -2.362984 NaN NaN
19 5 1.688877 NaN NaN
What is usually the resaon for this issue? I attach the corresponding report file.
I have also several questions related to GW calculations and it will be great if you can provide any advice.
1) In NSCF calculations of PWSCF, nbnd is set to be large like 1000, there are a few eigenvalues not fully converged. Will this be important and affect the GW calculations a lot? What can I do to solve this?
2) When I truncate Coulomb potential as a typical 2D material in Yambo, I find the calculated E_xc (-8.575967 Ry) by Yambo is not exact the same as the one in PWSCF (-8.57667827 Ry). They can be the same if I don't adopt the truncated c potential and RIM for integrals. Will this small difference affect the subsequent calculations in Yambo? Should I use assume_isolated='2D' to truncate Coulomb interaction in PWSCF as well?
3) What is the good signature of a converged GW correction? Should the variation of GW correction for the top VB and bottom CB be small than 0.01 eV? How is the accuracy of GW correction? I want a accurate GW bands not only the band gap.
4) Is it safe to always keep GDamping and dScStep default for a GW calculation?
5) Is it recommended to use Yambo 4.3 version? Someone told me Yambo 4.3 is more stable than Yambo 5.0.3.
Thanks a lot,
Changpeng