Inherent structure energy as the descriptor of mobility in glass formers

Search for the physics-based descriptor of mobility in glass formers has had a long history but remains largely unfulfilled. The configurational entropy proposed by Adam and Gibbs enjoys partial success in capturing the dependence of the main relaxation time on temperature, but fails to describe the dependence on anisotropic deformation. Within the potential energy landscape paradigm the minima, known as the inherent structures, and the saddle points are evaluated, where the latter are assumed to govern the relaxation processes and, hence, traditionally have been the focus of the studies. Using molecular dynamic simulations for several model glass formers, including both molecular and polymeric systems, we report that the mean inherent structure energy, rather than the potential energy barriers is the descriptor that unifies the effects of the temperature and the deformation on the relaxation time.