2022/03/11 by Francesco De Vita, De Vita, Francesco, Giovanni Dematteis +9
Materials Science · Physics and Astronomy · Engineering · #Material Dynamics and Properties #Nonlinear Photonic Systems #Adhesion, Friction, and Surface Interactions
paper · pdf · doi:10.48550/arxiv.2203.08627
One-dimensional particle chains are fundamental models to explain anomalous\nthermal conduction in low-dimensional solids like nanotubes and nanowires. In\nthese systems the thermal energy is carried by phonons, i.e. propagating\nlattice oscillations that interact via nonlinear resonance. The average energy\ntransfer between the phonons is described by the wave kinetic equation (WKE),\nderived directly from the microscopic dynamics. Here, we use the spatially\nnonhomogeneous WKE of the prototypical \β- Fermi-Pasta-Ulam-Tsingou (FPUT)\nmodel, equipped with thermostats able to set different temperatures at the two\nends. Our main findings are as follows: (i) The anomalous scaling of the\nconductivity with the system size, in close agreement with the known results\nfrom the microscopic dynamics, is due to a nontrivial interplay between high\nand low wavenumbers. (ii) The high-wavenumber phonons relax to local\nthermodynamic equilibrium transporting energy diffusively, it `a la\nFourier. (iii) The low-wavenumber phonons are nearly noninteracting and\ntransfer energy ballistically; this latter phenomenon is the analogous of the\nsecond sound emission, observed for example in superfluids.\n