The equation of state of an energy landscape

The topography of the multidimensional potential energy landscape is receiv ing much attention as a useful object of study for understanding complex be havior in condensed-phase systems. Examples include protein folding, the gl ass transition, and fracture dynamics in solids. The manner in which a syst em explores its underlying energy landscape as a function of temperature of fers insight into its dynamic behavior. Similarly, sampling in density, in particular the relationship between the pressure of mechanically stable con figurations and their bulk density (the equation of state of the energy lan dscape), provides fresh insights into the mechanical strength of amorphous materials and suggests a previously unexplored connection with the spinodal curve of a superheated liquid. Mean-field calculations show a convergence at low temperature between the superheated liquid spinodal and the pressure -dependent Kauzmann locus, along which the difference in entropy between a supercooled liquid and its stable crystalline form vanishes. This convergen ce appears to have implications for the glass transition. Application of th ese ideas to water sheds new light into this substance's behavior under con ditions of low-temperature metastability with respect to its crystalline ph ases.