Dynamical classification of metallic supercooled liquids: Critical cooling rates and entropic signatures

B Zhang and DM Zhang and DY Sun and XG Gong, JOURNAL OF CHEMICAL PHYSICS, 163, 034504 (2025).

DOI: 10.1063/5.0271636

Using molecular dynamics simulations, we systematically investigate supercooled liquids formed at cooling rates below and above the critical cooling rate (CCR). By analyzing the distribution of short-time averaged potential energies (DPE) and crystallization behaviors, we identify two distinct dynamical regimes in supercooled liquids: the glass-forming regime (GFR) and the crystal-forming regime (CFR). For systems cooled below CCR (CFR), the DPE exhibits a sharp peak, indicative of reduced configurational entropy. In contrast, liquids cooled above CCR (GFR) display a broad DPE distribution, reflecting higher configurational entropy. These findings establish a robust classification framework for supercooled liquids. Further analysis reveals a crossover temperature (T-x) in both regimes, consistent with the freezing temperature (T-f). Near T-x, crystallization barrier-temperature relationships exhibit abrupt changes. Below T-x, CFR crystallizes marginally faster than GFR, whereas above T-x, the influence of cooling rates on crystallization rates diminishes. These results further categorize GFR and CFR into high- and low-temperature sub-regimes, highlighting the interplay between thermodynamics and kinetics in supercooled liquids.

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