vibrations in amorphous materials

While in crystals heat is carried by propagating lattice waves, or phonons, in amorphous solids heat carriers are classified as propagons, diffusions, and locons depending on the degree of delocalization of the atomic vibration and its mean free path ¹².

In a-Si, prior works concludeed that non-propagating waves are the dominant contributors to heat transport, while propagating waves are restricted to frequency less than a few THz and are scattered by anharmonicity.

Current works on the thermal transport in a-Si:

• Heat transport in amorphous silicon: Interplay between morphology and disorder
  • Equilibrum molecular dynamics
• Thermal conductivity accumulation in amorphous silica and amorphous silicon
  • Normal-mode analysis
  • Plane-wave-like propogation is not affected by atomic disorder
• Examining the Validity of the Phonon Gas Model in Amorphous Materials
  • phonon gas model is not applicable to amorphous materials

• Dynamics structure factor

• propagating elastic waves dominate the thermal conduction and are scattered by elastic fluctuations rather than anharmonicity.
• explicitly demonstrate the propagating nature of vibration with frequency approaching 10 THz using a triggered wave computational experiment.