The physical mechanism of superconductivity is proposed on the basis of carrier-induced dynamic strain effect.
A superconducting material must simultaneously satisfy the following three necessary conditions required by superconductivity.
First, the material must possess the high-energy nonbonding electrons with certain concentrations requested by coherence lengths. Following this criterion, it is not surprising that most of alkaline metal, the covalent and closed-shell compounds, and the excellent conductors, copper, silver and gold do not show superconductivity at normal condition.
Second, the material must have the three-dimensional potential wells lying in energy at above the Fermi level of the material, and the dynamic bound state of superconducting electrons in potential wells of a given superconducting chain must have the same binding energy and symmetry.
Finally, in order to enable the normal state of the material being metallic, the band structure of the superconducting material must have a widely dispersive antibonding band, which crosses the Fermi level and runs over the height of potential wells.
On the basis of the mechanism of superconductivity proposed above, the key point to achieve superconductivity is that the superconducting electron must periodically exchange its excitation energy with chain lattice.