THERMODYNAMICS, DYNAMICS AND RELAXATION IN GLASS-FORMING LIQUIDS - THE CONFORMON CONCEPT

Any interpretation of the dynamics in liquids requires understanding of fluctuating collective motions in the stationary limit. To this end, ''eigen-states'' are defined, named conformons. Conformons are to be considered as a new type of bosons. Their properties characterize the typical features of the dynamics in disordered systems. Eigen-energy and ''eigen-entropy'' are adjusted to each other to minimize the free energy of each mode (saturation). The whole conformon ensemble exhibits a photon statistics with a broad universal mode spectrum. Analogues of Stefan-Boltzmann's law and of Wien's displacements law are formulated. A crucial point of our treatment is that conformons should, in principle, only become excited above a system-typical temperature T-o (Vogel-Fulcher temperature). Equilibrium properties of supercooled liquids are necessarily related to T-o. c(p)/c(v) of the conformon ensemble should, for example, show a typical Delta T-3-dependence (Delta T = T-T-o). Experimental data give evidence in support of this behaviour. As a consequence of the excluded volume supercooled liquids already solidify about 30 to 40 degrees above T-o at least at the quasi-static glass temperature T-g. Relaxation in the glass transition regime of glass formers can fully be described if relaxation modes are connected to each conformon. The description covers a set of experiments so different like mechanical and dielectric relaxation or quasi-elastic light- and neutron scattering.