CNR ExploRA

Articolo in rivista, 2017, ENG, 10.3390/e19090445

A chain, a bath, a sink, and a wall

Iubini S.; Lepri S.; Livi R.; Oppo G.-L.; Politi A.

Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, Sesto Fiorentino, I-50019, , Italy; Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Via G. Sansone 1, Sesto Fiorentino, I-50019, , Italy; Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del Piano 10, Sesto Fiorentino, I-50019, , Italy; SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, , United Kingdom; Institute for Complex Systems and Mathematical Biology, SUPA, University of Aberdeen, Aberdeen, AB24 3UE, , United Kingdom

We numerically investigate out-of-equilibrium stationary processes emerging in a Discrete Nonlinear Schrödinger chain in contact with a heat reservoir (a bath) at temperature TL and a pure dissipator (a sink) acting on opposite edges. Long-time molecular-dynamics simulations are performed by evolving the equations of motion within a symplectic integration scheme. Mass and energy are steadily transported through the chain from the heat bath to the sink. We observe two different regimes. For small heat-bath temperatures TL and chemical-potentials, temperature profiles across the chain display a non-monotonous shape, remain remarkably smooth and even enter the region of negative absolute temperatures. For larger temperatures TL, the transport of energy isstrongly inhibited by the spontaneous emergence of discrete breathers, which act as a thermal wall. A strongly intermittent energy flux is also observed, due to the irregular birth and death of breathers.The corresponding statistics exhibit the typical signature of rare events of processes with largedeviations. In particular, the breather lifetime is found to be ruled by a stretched-exponential law.

Entropy (Basel, Online) 19 (9)