I need information about reliability of BCS-Eliashberg-McMillan formalism especially for high Tc superconductors.
thank you very much Tapan chatterji sir. which model can be used to compute transition temperature of high Tc superconductors using pseudopotential?
Unfortunately there is not yet any theory that can compute Tc for these unconventional superconductors. So you cannot calculate.
The nature of the normal state and the mechanism of superconductivity in two families of high-temperature superconductors (HTSCs), cuprates and pnictides, remain a matter of intense discussions. So far there is no generally accepted view, so there is no formula for Tc .
Please accept my sincere gratitud Johan Frans Prins sir for the help you gave me. I'll go through your publication.
Well, from my point of view this question is based on a basic misconception. Neither BCS nor Eliashberg/McMillan ever claimed to be able to DETERMINE the critical temperature of a superconductor. The critical temperature T_c is the temperature at which a second order phase transition occurs. I don't know of any theory which is capable to determine the critical temperature (or some other critical parameter) of a second order phase transition from first principles. If there is one, I stay corrected! What BCS and/or Eliashberg proved was that when Cooper pairs exist (even one is enough) then there occurs a second order phase transition from the normal to the superconducting state at some critical temperature. If one wants to do actual calculations one has to fit an intrinsic parameter of the theory (BCS: N(0)V, Eliashberg: for instance the Coulomb pseudopotential \mu^\star) to give the experimental value of T_c. If one then calculates other superconducting properties one finds excellent qualitative (BCS) and even quantitative (Eliashberg) agreement between experiment and theory. The same holds for the various versions of the McMillan formula. Other information from sources external to BCS or Eliashberg will, of course, also help.
@ Johan Frans Prins - As the author of Physics Delusion I am not for a bit surprised by your pronouncements on this page. In my considered opinion you are wrong, on all accounts. The examples that you present to make your point (relating to doped semiconductors) are by no means relevant to the discussion at hand, not least by the fact that gap is not essential to superconductivity, a fact known since late 1950s, through a work by Abrikosov. And then of course calling the BCS model names goes far too far to be even amusing, not to say anything about denouncing the idea of phase transition.
@ Priank Kumar -- While largely agreeing with those on this page who express genuine criticism at the address of the BCS-Eliashberg-McMillan formalism, specifically in relation to the high-Tc superconducting compounds, just wish to add one remark not made by others thus far. The Eliashberg formalism relies on the validity of the Migdal theorem, which applies in the adiabatic limit, where the electronic and ionic degrees of freedom can be rigorously separated, that is where the Born-Oppenheimer approximation applies. When the Migdal theorem does not apply, there are very essential contributions that are systematically not accounted for by the Eliashberg formalism. Correcting for this shortcoming is not a trivial task. Insofar as I am aware, in the early days of the high-Tc superconductivity Luciano Pietronero (Rome) did some serious work on the subject matter, which you should be able to trace by doing a literature search.
@ Johan Frans Prins - I am not prepared to argue with someone who has mistaken this place with a gutter. Let me just suffice to mention that in my very considered opinion you are just a spammer, polluting the posts on Research Gate for reasons that you should know better than anyone else. It has been evident to me for a long time that you know no physics, but tolerated you out of a sense of community.
The answer is NO because at present few believe the electron-phonon interaction is responsible for high Tc shperconductivity, whereas the BCS-Eliashberg formalism is based exactly on this very interaction.
In addition the use of the McMillan formula is very much limited because it involves the Coulomb pseudopotential which, according to Hirsch, has been used as a wild card to fit this formula to almost any experimental measurement.
Dear Kumar, and friends in this discussion round table.There is a lot of confusion, first BCS + McMillan + Allen-Dynes + Eliashberg formulas are model dependent formulas, these formulas are not universal physics equations which we know in physics (like Maxwell equations for electrodynamics). These formulas are model dependent formulas, where the model describes only real materials which satisfy 4 approximations :
First, the adiabatic limit (called also Migdal approximation w0
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