On the dynamics of structural phase transitions

In order to gain insight into the critical dynamics of structural transitions, which are usually described by a Hamiltonian of linearly coupled anharmonic oscillators, the dynamic behaviour of a few coupled quartic oscillators is investigated. For single-well potentials and weak coupling, the displacement spectral function chi shows a single peak due to phonon vibrations. For double wells and single wells with strong coupling, chi has an additional resonance at low frequencies due to particles jumping from one well to the other. The relation between these results and other treatments of structural transitions is discussed.