  Molecular dynamics simulations of thiolate-protected and solvated gold
nanoparticles were carried out in the presence of a non-equilibrium heat flux
between the solvent and the core of the particle. The interfacial thermal
conductance ($G$) was computed for these interfaces, and the behavior of the
thermal conductance was studied as a function of particle size, ligand
flexibility, and ligand chain length. In all cases, thermal conductance of the
ligand-protected particles was higher than the bare metal-solvent interface. A
number of mechanisms for the enhanced conductance were investigated, including
thiolate-driven corrugation of the metal surface, solvent ordering at the
interface, solvent-ligand interpenetration, and ligand ordering relative to the
particle surface. Only the smallest particles exhibited significant
corrugation. All ligands permitted substantial solvent-ligand interpenetration,
and ligand chain length has a significant influence on the orientational
ordering of interfacial solvent. Solvent-ligand vibrational overlap,
particularly in the low frequency range ($< 80 \mathrm{cm}^{-1}$) was
significantly altered by ligand rigidity, and had direct influence on the
interfacial thermal conductance.
