Yambo Community Forum

Dear sir,

I have plotted the GW band structure with quasi particle correction but the band gap is increasing too much and not matching with the experimental results. To calculate the band structure with QP correction I have first done ground state calculations from quantum espresso and then first GW calculation and then second GW calculation with GfnQPdb= "E < gw_out/ndb.QP".
What i need to do now?


Regards,
Himani Mishra
Research Scholar
IIIT Allahabad

Dear Himani,
if GW gap does not match experiments there could infinite reasons for that. Starting from the fact that GW is an approximation.
Moreover as you do not post any input and report it is not possible to see if you did some mistakes etc..
I suggest you first of all to check carefully all the convergences if you did not already (bands in the screening, bands in GW summation, Gblock in the screening, kpoints, etc..).

Finally, from your post it looks you did 2 GW calculations, including QP eigenvalues in the Green function of the second calculation,
are you trying to do an eigenvalues only self consistency?,
did you reach convergence with just 2 iterations?

Best,

Daniele