Year: 1999
Type: preprint
Abstract: Dynamical heterogeneity and the decoupling of diffusion and structural relaxation in a supercooled liquid is investigated in terms of a time-dependent, fourth-order density correlation function. The generalized susceptibility $χ_4(t)$ corresponding to this correlation function has a maximum at an intermediate time $t_4^*$, and both $t_4^*$ and $χ_4(t_4^*)$ grow strongly with decreasing temperature. We show that the main contribution to $χ_4(t)$ arises from spatial correlations between temporarily localized (``caged'') particles. We compare $χ_4(t)$ with a generalized susceptibility $χ_M(t)$ related to a correlation function of squared particle displacements, and show that while $t_4^*$ is roughly proportional to the $α$-relaxation time, $t_M^*$ is proportional to the inverse of the self-diffusion coefficient.
Source: arXiv (Cornell University)
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1748136767