Fast Vibrational Modes and Slow Heterogeneous Dynamics in Polymers and Viscous Liquids
arXiv:1911.07521 · doi:10.3390/ijms20225708
Abstract
Many systems, including polymers and molecular liquids, when adequately cooled and/or compressed, solidify into a disordered solid, i.e., a glass. The~transition is not abrupt, featuring progressive decrease of the microscopic mobility and huge slowing down of the relaxation.} A~distinctive aspect of glass-forming materials is the microscopic dynamical heterogeneity (DH), i.e., the presence of regions with almost immobile particles coexisting with others where highly mobile ones are located. Following the first compelling evidence of a strong correlation between vibrational dynamics and ultraslow relaxation, we posed the question if the vibrational dynamics encodes predictive information on DH. Here, we review our results, drawn from molecular-dynamics numerical simulation of polymeric and molecular glass-formers, with a special focus on both the breakdown of the Stokes--Einstein relation between diffusion and viscosity, and the size of the regions with correlated displacements.
23 pages, 10 figures
References in corpus (7)
- Theoretical perspective on the glass transition and amorphous materials
- Irreversible reorganization in a supercooled liquid originates from localised soft modes
- Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids
- Short and long range correlated motion observed in colloidal glasses and liquids
- Thermodynamic scaling of vibrational dynamics and relaxation
- Non-gaussian effects in the cage dynamics of polymers
- Assessment of elastic models in supercooled water: A molecular dynamics study with the TIP4P/2005f force field