Examining normal modes as fundamental heat carriers in amorphous solids: the case of amorphous silicon

Abstract

Normal mode decomposition of atomic vibrations has been used to provide microscopic under-standing of thermal transport in amorphous solids for decades. In normal mode methods, it is naturally assumed that atoms vibrate around their equilibrium positions and that individual normal modes are the fundamental vibrational excitations transporting heat. With the abundance of predictions from normal mode methods and experimental measurements now available, we care-fully analyze these calculations in amorphous silicon, a model amorphous solid. We find a number of discrepancies, suggesting that treating individual normal modes as fundamental heat carriers may not be accurate in amorphous solids. Further, our classical and ab-initio molecular dynamics simulations of amorphous silicon demonstrate a large degree of atomic diffusion, especially at high temperatures, leading to the conclusion that thermal transport in amorphous solids could be better described starting from the perspective of liquid dynamics rather than from crystalline solids

References in corpus (3)

• Measuring the dynamic structure factor of a quantum gas undergoing a structural phase transition
• Origin of micron-scale propagation lengths of heat-carrying acoustic excitations in amorphous silicon
• Akhiezer Mechanism Dominates Relaxation of Propagons in Amorphous at Room Temperature

Cited by in corpus (4)

• Mechanisms of temperature-dependent thermal transport in amorphous silica from machine-learning molecular dynamics
• Atomic dynamics in fluids: Normal mode analysis revisited
• Transport and relaxation of current-generated nonequilibrium phonons from nonlocal electronic measurements
• The origin of strings and rings in the atomic dynamics of disordered systems