Dear QE users and developers, Recently, I was trapped by a question about the critical temperature Tc for a very long time. In one calculation, I can successfully get the lamda (electron-phonon coupling) and Tc like: lambda omega_log T_c 0.15006 335.625 0.000 0.23881 279.676 0.007 0.37627 249.217 0.724 0.55241 226.383 3.971 0.74555 208.449 8.401 0.93962 193.607 12.205 1.12670 180.939 14.944 ... ... ....
But when I add two flags: el_ph_sigma=0.005, el_ph_nsigma=10, into the system. elph.in file. I obtained the result: lambda omega_log T_c 0.05937 1332.783 ********* 0.06470 1324.945 ********* 0.06835 1309.450 ********* ... ... .... I compare the phonon dispersion, both are identical and without imaginary frequency. I also check the elph.inp_lambda.* file, no imaginary frequency also. I use the pwscf 6.3 version. Both calculations are identical except for these two parameters (without/with).* Lamda changes significantly.* *I am wondering how much effect of these two flags in pwscf on the superconductivity?* I checked the manual, but the related info is limited. In the latest version of 6.4, the official website has deleted these two flags. Why these two parameters would lead to the infinite Tc? Thanks a lot! Best wishes, Zhibin Tongji University
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