[Pw_forum] Lambda of the el-ph interaction

[Malgorzata Wierzbowska]

On Thu, 8 Feb 2007, [big5] 陳 少華 wrote:

> Dear members,
> How small of Lambda of the el-ph interaction that we
> can say it is weak-coupling  which not suit for
> strong-coupled McMillan transition Tc formula ?   Is
> Lambda < 0.2 ?
>

    Hi Max,
    The McMillan formula gives the best possible approximation to Tc
    when the Debye frequency is close to the frequency of
    the maximum of the Eliashberg function.
    If you know the s2F function it is better to use Allen and Dynes
    formula or modified Allen and Dynes formula (if lambda >> 1)
    See PRB vol 12, 905 (1975).
    Recent, the best in my opinion, for Tc is:
    Oliveira, Gross and Kohn PRL vol 60, 2430 (1988) and later development,
    you can find it in psi_k network in highlights:
    http://psi-k.dl.ac.uk/index.html?highlights (DFT for superconductors).

    Gosia


> Best Regards
> max
>
>
> ___________________________________________________
> 您的生活即時通 － 溝通、娛樂、生活、工作一次搞定！
> http://messenger.yahoo.com.tw/
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>