Spectral Decomposition of Liquid Viscosity into Instantaneous Normal Modes (opens in new tab)

Viscosity, the resistance of a liquid to flow, is driven by atomic-scale friction but its microscopic origin remains poorly understood. We use a theoretical framework based on nonaffine linear response to decompose the viscosity of metallic and model liquids into contributions from individual instantaneous normal modes (INMs). Our approach reveals excellent agreement with simulations and exposes the specific excitations that govern viscous d...