Elastic properties of A15 structure superconductors

The polaron effect induced renormalization of phonon spectrum of superconducting compounds with an A15 structure is considered.The microscopic expression for Poisson's ratio σ with no empirical parameters involved is derived in terms of the constant of electron-phonon coupling λ. The calculated data on σ (λ) and σ (T) for transition metals and alloys as well as for six A15 compounds with the well-known elastic properties are in good agreement with experimental results. The elastic characteristics of 30 A15 compounds for which there are no experimental data available are calculated.