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Hello,

I am trying to calculate the band opening of graphene at the K-point under a uniaxial strain in graphene. I already calculated these using
LDA. However, I want to improve the results for the band gap by performing GW calculations. I followed the tutorial regarding GW calculations
and calculated the band gap with the GW correction for ngkpt (18 18 1). When I increase ngkpt to (24 24 1) or higher and leave everything else
exactly the same I suddenly get NaN results in the calculations (see below). Any help is appreciated.


Using GW18.in I get

k = -0.333 0.333 0.000
Band E_lda <Vxclda> E(N-1) <Hhartree> SigX SigC[E(N-1)] Z dSigC/dE Sig[E(N)] DeltaE E(N)_pert E(N)_diago
4 -0.971 -13.920 -0.971 12.949 -12.638 -1.073 0.714 -0.401 -13.771 0.149 -0.822 -0.762
4 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
5 -0.824 -13.904 -0.824 13.080 -12.189 -1.415 0.714 -0.401 -13.690 0.214 -0.610 -0.525
5 0.000 0.000 0.000 0.000 0.000 -0.000 0.000 0.000 -0.000 -0.000 -0.000 0.000

E^0_gap 0.147
E^GW_gap 0.212
DeltaE^GW_gap 0.064


For GW24.in, which is exactly the same except a denser k-grid I get

k = -0.333 0.333 0.000
Band E_lda <Vxclda> E(N-1) <Hhartree> SigX SigC[E(N-1)] Z dSigC/dE Sig[E(N)] DeltaE E(N)_pert E(N)_diago
4 -0.972 -13.920 -0.972 12.948 NaN NaN NaN NaN NaN NaN NaN NaN
4 0.000 0.000 0.000 0.000 0.000 NaN NaN 0.000 NaN NaN NaN 0.000
5 -0.824 -13.904 -0.824 13.080 NaN NaN NaN NaN NaN NaN NaN NaN
5 0.000 0.000 0.000 0.000 0.000 NaN NaN 0.000 NaN NaN NaN 0.000

writing QP data on file : tmpo_DS4_QPS