Open Conference Systems, StatPhys 27 Main Conference

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Thermal conductivity in nanopatterned Si membranes: statistical aspects of the equilibration stage .
Agustin Matias Mancardo Viotti, Maria Florencia Carusela, Alejandro Gabriel Monastra

##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


For low dimensional systems, in the scale of nanometers, thermal properties strongly depend on the size of the system, the coupling with the environment, the spectral density of the reservoirs and stress state, among others.

For example, to compute thermal conductivity, a stationary non-equilibrium regime is required. In this case, the system is connected to thermal reservoirs at different temperatures. The stablished thermal current should achieve a constant value and, via the Fourier law, the thermal conductivity is estimated.

Time scales to reach the stationary regime can be larger or shorter depending on “how good” the initial state is. Consequently it is important to start from a proper equilibrium state.

For this purpose we study in detail this equilibration stage to compute thermal transport properties of a Si-nanomembrane, with potential technological interest.

Thermodynamical fluctuations are large for small finite systems, however, potential energy can take long time to achieve an equilibrium value. This is an indication that the surface may not yet be reconstructed, due to the large surface to volumen ratio.

Another relevant feature in the equilibration stage is the internal stress. In order to simulate more realistic suspended membranes, this stress should be strongly reduced.

In those studies where periodic boundary conditions are considered, these aspects are not usually taken into account because the finite size effect is washed up.

We analyze different protocols to efficiently reach the equilibrium state in reasonable computational times. The numerical study is based on molecular dynamics simulations using the software LAMMPS.