Dear Prof Warren, Yes, QE uses the Allen-Dynes equation to determine the Tc.
I appreciate your additional insight in to the value of lambda. We're reexamining to ensure that computational errors and noises are ruled out. Then conclusive inference can be made from the result. Your response is really appreciated. Isaiah. On Fri, Jul 28, 2017 at 3:18 PM, Warren Pickett <[email protected]> wrote: > Isaiah, > > I'm not familiar with the workings of QE, but without solution of the > full Eliashberg equations it must be using the Allen-Dynes equation (as > most do) to obtain Tc. > > The basic fact is that with a standard Coulomb repulsion mu-star = > 0.10-0.15, with lambda less than 0.3 or so there will be no > superconductivity. The A-D equation was not fit to tiny values of Tc and no > one should be interested in those results. If non-zero, they will be > extremely sensitive to lambda, as you can see. [And you can get > nonsensical large values! as you can see] > > So just accept that if lambda < 0.3 or so, any results cannot be trusted > and its not an interesting el-ph superconductor. > > Warren > > > Warren E. Pickett > Distinguished Professor of Physics > Department of Physics > University of California Davis > Davis CA 95616, USA > Cell: 530-220-2138 > > On Fri, Jul 28, 2017 at 12:24 AM, Isaiah Moses <[email protected]> wrote: > >> Dear everyone, >> >> I did an el-ph calculation of a monoclinic structure and am getting >> really strange values of Tc . See the result below >> lambda omega_log T_c >> 0.00994 112.048 0.10012314E+08 >> 0.03760 92.373 0.13380511E+10 >> 0.07564 90.247 0.39802174E+19 >> 0.09959 89.414 0.19865362E+78 >> 0.11010 89.463 0.40671597-151 >> 0.11454 90.329 0.16986711E-65 >> 0.11678 92.320 0.99512429E-51 >> 0.11772 94.657 0.29927798E-46 >> 0.11744 97.141 0.16242032E-47 >> 0.11619 99.442 0.65514785E-54 >> >> I'm wondering why such values. >> >> Any comment shall be greatly appreciated. >> >> Thanks, >> Isaiah >> >> -- >> Isaiah Abu Moses >> Graduate Student, >> Physics Department, >> University of Ibadan, >> Nigeria >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Isaiah Abu Moses Graduate Student, Physics Department, University of Ibadan, Nigeria
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