  In this paper, equilibrium molecular dynamics simulations were performed on
Au-SAM (self-assembly monolayer)-Au junctions. The SAM consisted of
alkanedithiol molecules. The out-of-plane (z-direction) thermal conductance and
in-plane (x- and y-direction) thermal conductivities were calculated.
Simulation finite size effect, gold substrate thickness effect, temperature
effect, normal pressure effect, molecule chain length effect and molecule
coverage effect on thermal conductivity/conductance were studied. Vibration
power spectra of gold atoms in the substrate and sulfur atoms in the SAM were
calculated and vibration coupling of these two parts was analyzed. The
calculated thermal conductance values of Au-SAM-Au junctions are in the range
of experimental data on metal-nonmetal junctions. The temperature dependence of
thermal conductance has similar trend to experimental observations. It is
concluded that the Au-SAM interface resistance dominates thermal energy
transport across the junction, while the substrate is the dominant media in
which in-plane thermal energy transport happens.
