  The physical mechanism of superconductivity is proposed on the basis of
carrier-induced dynamic strain effect. By this new model, superconducting state
consists of the dynamic bound state of superconducting electrons, which is
formed by the high-energy nonbonding electrons through dynamic interaction with
their surrounding lattice to trap themselves into the three - dimensional
potential wells lying in energy at above the Fermi level of the material. The
binding energy of superconducting electrons dominates the superconducting
transition temperature in the corresponding material. Under an electric field,
superconducting electrons move coherently with lattice distortion wave and
periodically exchange their excitation energy with chain lattice, that is, the
superconducting electrons transfer periodically between their dynamic bound
state and conducting state. Thus, the intrinsic feature of superconductivity is
to generate an oscillating current under a dc voltage. The coherence lengths in
cuprates must have the value equal to an even number times the lattice
constant. A superconducting material must simultaneously satisfy three criteria
required by superconductivity. Almost all of the puzzling behavior of the
cuprates can be uniquely understood under this new model. We demonstrate that
the factor 2 in Josephson current equation, in fact, is resulting from 2V, the
voltage drops across the two superconductor sections on both sides of a
junction, not from the Cooper pair, and the magnetic flux is quantized in units
of h/e, postulated by London, not in units of h/2e. The central features of
superconductivity, such as Josephson effect, the tunneling mechanism in
multijunction systems, and the origin of the superconducting tunneling
phenomena, are all physically reconsidered under this superconductivity model.
