Dynamic aspects of the liquid-liquid phase transformation in silicon.
First principles molecular dynamics simulations are used to characterize dynamic properties of supercooled liquid silicon across the liquid-liquid phase transition. Our results evidence the presence of a boson peak in the terahertz frequency range for the low-density liquid and support the scenario of a fragile-to-strong transition. The analysis of the collective excitations shows that its origin is due to a coupling of the longitudinal and transverse acoustic modes localized on the nanometer scale and can be attributed to collective vibrations of connected tetrahedra.
Jakse
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Sciences et Ingenierie des Materiaux et Procedes, UMR 5266, INP Grenoble, UJF-CNRS, 1130, rue de la Piscine, BP 75, 38402 Saint-Martin d'Heres Cedex, France. noel.jakse@ltpcm.inpg.fr
Pasturel
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