What is it about?
Silicon is a network-forming liquid like water. It exhibits signature anomalies in structure, dynamics and thermodynamics. Here we analyze the relationship among different characteristic timescales such as diffusion coefficient, shear viscosity η and structural relaxation times τ at different probe lengthscales, over a broad range of temperature (T) and pressure (P) spanning both normal and anomalous regimes using extensive computer simulation.
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Why is it important?
By analyzing the relationship among various characteristic timescales, we clarify to what extent the anomalies influence dynamics in silicon. We identify a new type of behaviour at high temperature indicating that network-forming liquids have a richer set of dynamical behaviour than colloidal and metallic glass-formers. We compute two key observables - (i) shear viscosity and (ii) a dynamical lengthscale characterizing the emergent many-body correlation in the supercooled regime, for the first time in silicon to the best of our knowledge. Our study should motivate further work to explain the observed behaviours by microscopic pictures such as the two state model.
Perspectives
We found this investigation interesting because the characteristics of liquid silicon may provide a better understanding of the network-forming liquids and uncover the underlying dynamics. Our investigation stemmed from a fundamental need to understand how structure and dynamics interact in systems with directional bonding. [Thoughts from Himani Rautela, first author of this study.]
Shiladitya Sengupta
Indian Institute of Technology Roorkee
Read the Original
This page is a summary of: Breakdown of the Stokes–Einstein relation in Stillinger–Weber silicon, The Journal of Chemical Physics, April 2025, American Institute of Physics,
DOI: 10.1063/5.0256328.
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