Aging and Energy Landscapes: Application to Liquids and Glasses
  The equation of state for a liquid in equilibrium, written in the potential energy landscape formalism, is generalized to describe out-of-equilibrium conditions. The hypothesis that during aging the system explores basins associated to equilibrium configurations is the key ingredient in the derivation. Theoretical predictions are successfully compared with data from molecular dynamics simulations of different aging processes, such as temperature and pressure jumps. 
Stefano Mossa, Emilia La Nave, Francesco Sciortino, and Piero   Tartaglia