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Dynamical phase transitions in Kob-Andersen model investigated by trajectory energy-biased ensemble method
Jiho Son1, Jay-Hak Lee1,2, YounJoon Jung1
1Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea.
The Journal of Chemical Physics
|May 26, 2026
Summary
Energy biasing alone can induce first-order dynamical phase transitions in glass-forming models. This study establishes the g-ensemble as a framework connecting energy landscapes to dynamical arrest in the glass transition.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
- Computational Physics
Background:
- Statistical mechanics of non-equilibrium systems relies on trajectory ensembles.
- Biasing fields, like s-field and g-field, probe rare dynamical states.
- Previous studies explored s-ensembles, but energy-only biasing effects were unclear.
Purpose of the Study:
- Investigate if energy-only biasing (g-field) can induce dynamical phase transitions.
- Construct the two-dimensional (T, g) phase diagram for the Kob-Andersen model.
- Understand the relationship between energy landscape and dynamical arrest.
Main Methods:
- Transition path sampling to construct the phase diagram.
- Binder cumulant analysis with Gaussian process regression and large-deviation relations.
- Analysis of dynamical susceptibilities, order parameter distributions, and intermediate scattering functions.
Main Results:
- Identified a first-order dynamical phase transition line separating active and inactive trajectory phases.
- Located the upper critical point at (Tuc, guc) ≃ (0.675, 1.9 × 10-3).
- Demonstrated that g-ensemble glasses are structurally identical to conventionally quenched glasses, with the transition being purely dynamical.
Conclusions:
- Energy-landscape biasing alone drives first-order dynamical phase transitions in atomistic glass-forming models.
- The g-ensemble provides a controlled framework linking potential energy landscapes to dynamical arrest.
- Results support the dynamical facilitation picture of the glass transition.
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