what are Z and lam printed in epw output

[Gautam Sharma Monty]

Dear Sir,

I am calculating electron-self energy of bulk system. I have obtained the linewidth.elself files. But I wonder what is quantity printed in epw.out file, that are labelled by "Z" and "lam" printed after the Re[Sigma] and Im[Sigma]?
Is "lam" el-ph coupling strength given by (1)?
What is "Z" here and what is if is negative number b/w 0 and 1, does it has any physical meaning?


(1) ?$_{q?}$=1N(?F)?$_{q?}$?$_{nm}$?BZdk?$_{BZ}$|g_{mn},?(k,q)|2?(?$_{nk}$??_F)?(?$_{mk}$+q??_F) ,

This is equation (11) as mentioned in EPW paper (arxiv): (EPW: Electron-phonon coupling, transport and superconducting properties usingmaximally localized Wannier functions)

[sponce]

Dear Gautam,

The Z is the correction factor obtained via linearization to account for the fact that the electron self-energy should be evaluated at the renormalized
eigenvalues but they are evaluated at the bare KS eigenvalue.

E_nk = e_nk + Re Sigma(E_nk)
E_nk \approx e_nk + Z_nk Re Sigma(e_nk)

Best,
Samuel