Theory of phase transitions in the -tungsten structure induced by the band jahn-teller effect

A dynamic theory of the cubic-to-tetragonal transformation in the -tungsten structure is presented starting with a Hamiltonian describing the interaction between static strain and acoustic phonons with the electrons in the triply degenerate d bands. For this model the elastic constants are strongly temperature dependent in the low-frequency limit. However, for frequencies in the neighborhood of the Debye frequency, they are nearly temperature independent. © 1971 The American Physical Society.