The phase space structure of supercooled liquids: Evidence of a dynamical critical temperature

We calculate local potential energy minima (inherent structures) for a simple model of orthoterphenyl (OTP), from computer simulations over a wide temperature range. We show that the results are very sensitive to the system size. We locate, from the temperature and size dependence of inherent structure energies, a well defined cross-over temperature that corresponds to the dynamical critical temperature predicted by mode coupling theory and in mean field spin glass models. Comparing the known phase space structure of mean field $p$-spin models and the present results for the OTP model, we find evidence supporting the proposed similarity between glass-forming liquids and a class of spin glass models.