# Thermodynamics–Structure–Dynamics Correlations and Nonuniversal Effects in the Elastically Collective Activated Hopping Theory of Glass-Forming Liquids

journal contribution

posted on 07.07.2020, 13:14 by Baicheng Mei, Yuxing Zhou, Kenneth S. SchweizerWe
employ the microscopic Elastically Collective Nonlinear Langevin
Equation (ECNLE) theory of activated dynamics in combination with
crystal-avoiding simulations to study four inter-related questions
for metastable monodisperse hard sphere fluids. The first is how significantly
improved integral equation theory structural input (Modified-Verlet
(MV) closure) changes the dynamical predictions of ECNLE theory. The
main consequence is a modest enhancement of the importance of the
collective elastic barrier relative to its local cage contribution,
which increases the alpha relaxation time and fragility relative to
prior results based on the Percus–Yevick closure. Second, ECNLE-MV
theory predictions for the alpha time and self-diffusion constant
in the metastable regime are quantitatively compared to our new simulations.
The small adjustment of a numerical prefactor that enters the collective
elastic barrier leads to quantitative agreement over three decades.
Third, using the more accurate MV structural input, ECNLE theory is
shown to predict thermodynamics–structure–dynamics “correlations”
based on various long and short wavelength scalar properties all related
to static two-point collective density fluctuations. The logarithm
of the alpha relaxation time scales as a power law with these scalar
metrics with an exponent that is significantly lower in the less dense
noncooperative activated regime compared to the very dense highly
cooperative regime. However, the discovered correlation of activated
relaxation with a thermodynamic property (dimensionless compressibility)
is not causal in ECNLE theory, but rather reflects a strong connection
between the local structural quantities that quantify kinetic constraints
in the theory with the amplitude of long wavelength density fluctuations.
Fourth, the consequences of chemically specific nonuniversalities
associated with the onset condition and relative importance of collective
elasticity are studied. The predicted thermodynamics–structure–dynamics
correlations are found to be robust, albeit with nontrivial shifts
of the onset condition.