Abstract
We examine correlations of transverse particle displacements and their relationship to the shear modulus of a glass and the viscosity of a fluid. To this end we use computer simulations to calculate a correlation function of the displacements, , which is similar to functions used to study heterogeneous dynamics in glass-forming fluids. We show that in the glass the shear modulus can be obtained from the long-time, small- limit of . By using scaling arguments, we argue that a four-point correlation length grows linearly in time in a glass and grows as at long times in a fluid, and we verify these results by analyzing obtained from simulations. For a viscoelastic fluid, the simulation results suggest that the crossover to the long-time growth of occurs at a characteristic decay time of the shear stress autocorrelation function. Using this observation, we show that the amplitude of the long-time growth is proportional to where is the viscosity of the fluid.
- Received 12 May 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.025501
© 2015 American Physical Society