Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Andrea Saverio Ninarello; Nicoletta Gnan; Francesco Sciortino

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arXiv · 1406.6226

Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Andrea Saverio Ninarello·Nicoletta Gnan·Francesco Sciortino

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Abstract

We discuss the observable-dependence of the effective temperature $T_{eff}$, defined via the fluctuation-dissipation relation, of an out-of-equilibrium system composed by homonuclear dumbbell molecules. $T_{eff}$ is calculated by evaluating the fluctuation and the response for two observables associated respectively to translational and to rotational degrees of freedom, following a sudden temperature quench. We repeat our calculation for different dumbbell elongations $ζ$. At high elongations ($ζ> 0.4 $), we find the same $T_{eff}$ for the two observables. At low elongations ($ζ\leq 0.4$), only for very deep quenches $T_{eff}$ coincides. The observable-dependence of $T_{eff}$ for low elongations and shallow quenches stresses the importance of a strong coupling between orientational and translational variables for a consistent definition of the effective temperature in glassy systems.

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Andrea Saverio Ninarello, Nicoletta Gnan, Francesco Sciortino. 2014-06-24. Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids. https://arxiv.org/abs/1406.6226

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