Open Conference Systems, StatPhys 27 Main Conference

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Non linear fluctuating hydrodynamic theory applied to a stressed anharmonic chain in 3D
Alejandro G. Monastra, M. Florencia Carusela, Roberto Barreto

##manager.scheduler.building##: Edificio Santa Maria
##manager.scheduler.room##: Auditorio San Agustin
Date: 2019-07-08 11:45 AM – 03:30 PM
Last modified: 2019-06-15

Abstract


Based on recent numerical studies on anomalous thermal transport in low dimensional systems [1,2], we extend previous works on non-linear fluctuating thermodynamics theory (NLFHT) applied to anharmonic chains [3,4] to 3D motion.

The model consists of a chain of atoms that interact up to first neighbors with a general non-linear potential depending only on the distance. One end of the chain is fixed, while the other is subjected to an external constant force, which causes a tension and strain along it. The external tension works as a negative pressure, being an external parameter that can be controled. Both features are in contrast to other works, where usually periodic boundary conditions and positive or zero pressure are used.

This model could be applied to realistic systems such as polymers and nanowires in experimental conditions.

In the framework of NLFHT, vibrations in 3D provides seven conserved fields. From these fields we obtain, at linear order, two longitudinal sound modes, four transversal sound modes and one heat mode.

We focus on the spatio-temporal correlations of these modes. For long time, the crossed correlations between different modes vanish. Thus, we concentrate on the autocorrelations and the broadening of these peaks in time.

We observe that in this decoupled regime, the time evolution of the modes corresponds to the structure of the noisy Burgers equation. For the longitudinal sound modes and the heat mode we find a superdiffusive behaviour, meanwhile for the transversal sound mode a diffusive one.

The theoretical results are contrasted by molecular dynamics simulations.

[1] R. Barreto, M. F. Carusela, and A. Monastra, J. Stat. Mech. Theory Exp., 103201 (2017)

[2] A. V. Mancardo, A. Monastra, M. Moreno, and M.F. Carusela, J. Stat. Mech. Theory Exp., 083201 (2016)

[3] H. Spohn, Fluctuating Hydrodynamics Approach to Equilibrium Time Correlations for Anharmonic Chains, Chapter 3 in Thermal Transport in Low Dimensions From Statistical Physics to Nanoscale Heat Transfer, Lecture Notes in Physics 921, S. Lepri Editor (2016)

[4] S. G. Das, A. Dhar, K. Saito, C. B. Mendl, and H. Spohn, Phys. Rev. E 90, 012124 (2014)