10 - Glasses and supercooled liquids

Summary

In this final chapter we consider applications of energy landscape theory to structural glasses and supercooled liquids. The ultimate objective of this approach is to understand and predict how the glass transition and associated phenomena depend upon details of the underlying potential energy surface. The large number of different models proposed to explain the glass transition must partly reflect different ways of expressing similar ideas, as well as the fundamental importance of the problem (1, 2). An overview of some of these theoretical methodologies is given in Section 10.1. Detailed comparisons between theory and experiment for properties such as dielectric loss (3, 4) or light-scattering spectra (5, 6) of a molecular glass former clearly present a significant challenge, and hence discrimination between different models is relatively hard.

The most popular systems for computer simulations of structural glass formers are described in Section 10.2. Surveys of local minima and transition states, including theoretical approaches based on the superposition framework, are treated in Section 10.3 and Section 10.4, and results for model potential energy surfaces are summarised in Section 10.5. The influence of the system size on the PES is analysed in Section 10.6, where properties of the configuration space are compared with the scaling laws expected for random networks.