Open AccessExperimental test of a predicted dynamics–structure–thermodynamics connection in molecularly complex glass-forming liquids
Author(s) -
Baicheng Mei,
Yuxing Zhou,
Kenneth S. Schweizer
Publication year - 2021
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2025341118
Subject(s) - dimensionless quantity , relaxation (psychology) , thermodynamics , elasticity (physics) , statistical physics , compressibility , viscosity , molecular dynamics , diffusion , crossover , chemical physics , materials science , chemistry , physics , computational chemistry , computer science , psychology , social psychology , artificial intelligence
Significance The physical origin of cooperative activated relaxation in glass-forming liquids, which underlies the huge growth of viscosity and suppression of diffusion with cooling, remains elusive. Understanding this problem is of fundamental scientific interest and can assist in the design of new materials. We combine experimental relaxation time and equation-of-state data of molecular liquids to provide strong evidence for the recent theoretical prediction that activated relaxation, though causally driven by dynamically coupled cage-scale hopping and nonlocal collective elasticity quantified by local structural correlations, is well captured based on a thermodynamic description with dimensionless compressibility as the key variable. A mechanistic deduction is the crossover from fragile to strong (e.g., inorganic networks) relaxation behavior arises from the irrelevance of long-range elasticity effects.