• Data: 3 kwietnia 2019
• Godzina: 10¹⁵
• Temat: Molecular arrest induced by the spatially correlated stochastic dynamics.
• Autor: Dr Maciej Majka, Instytut Fizyki im. Mariana Smoluchowskiego, Uniwersytet Jagieloński, Kraków
• Adres: sala P/1/13, SMCEiBI w Chorzowie

Abstract:

Spatially correlated noise (SCN), i.e. the thermal noise that affects neighbouring particles in a similar manner, is ubiquitous in soft matter systems. In this presentation, the fluctuation-dissipation  relation for SCN is derived to show that it can induce the molecular  arrest. This behaviour resembles glass transition, i.e. the critical  slow-down of dynamics in the dense disordered systems. As a model, the over-damped SCN-driven Langevin dynamics with collective friction matrix is employed. It will be shows that the mechanism of singular dissipation is embedded in this matrix. The characteristic length of collective dissipation is also identified, which diverges at the critical packing. This quantity grasps the qualitative shift from the ergodic to non-ergodic dynamics, as the density in a disordered system is increased. The model is fully nalytically solvable, one-dimensional and admits arbitrary interactions between particles. As a practical example, both the hard spheres and the systems of  ultra-soft particles are studied. The transition is controlled by the interplay between the packing fraction and the noise correlation length. The model can be effectively compared to the mode coupling theory. The results suggest that spatial correlations might act as a direct cause of arrest and high viscosity.