Dynamics and structure of liquid and supercooled liquid m-toluidine investigated by molecular dynamics simulations

Molecular dynamics simulations have been performed to investigate the structure and the dynamics of supercooled liquid m-toluidine. At the critical temperature Tc predicted by the mode coupling theory, where a transition from an ergodic to a nonergodic dynamical regime is observed, we found evidence of a drastic structural phase transition. This transition involving pairs of H-bonded molecules is due to a change of their reciprocal arrangement. Although this study is limited to a particular system, m-toluidine, it has sufficient generality to allows us to suggest that dynamical relaxation in liquids might be strongly molecular shape-dependent and that future developments of dynamical theories of the supercooled liquid state, such as the mode coupling theory, must be devised to include the influence of the molecular structure, overcoming the particle-shapeless assumption.