The ability to simulate the optical response of plasmonic linker gels has also been used to discover new design rules for mechano-optical response. Specifically, using molecular dynamics simulations together with MPM calculations, the evolution of the near-and farfield spectra was studied for polymer-linked plasmonic nanoparticle gels. As hypothesized by Howard et al., a mixture of short and long linking molecules led to gels with a qualitatively different mechano-optical response than those with a single type of linker with the mixture's average molecular weight (Figure ). In the mixed linker gels, clusters of nanoparticles connected by short linkers largely preserved their local near-field coupling under uniaxial strain, while the longer linkers extended to accommodate the deformation. Other mechanical properties were insensitive to the linker molecular weight distribution, meaning the proportion of short linkers could be used to independently tune the nature of the mechano-optical response. These predictions provide a microscopic interpretation of how metal nanoparticle clustering in experimental polymer nanocomposites gives rise to polarization-dependent shifts of collective plasmon resonances under uniaxial deformation that run counter to intuitive expectations for the changing particle distances under affine deformation. The optical properties of plasmonic nanocrystal gels, when combined with structural analysis tools such as SAXS, also offer new mechanistic insights into gel aging. For instance, the temporal evolution of ITO nanocrystal gel structure and optical properties were monitored using SAXS and UV-Vis-NIR spectroscopy, respectively, under varying noncoordinating salt concentrations ([TBAPF 6 ]). Gels linked by a dihydrazone moiety, formed by aldehyde terminal groups of ligands and dihydrazide linker molecules, exhibited higher SAXS structure factor S(q) at low wavevector q and collective plasmon resonances with lineshapes that were broadened and shifted to lower energies with increased [TBAPF 6 ] (Figure ). Simulations conducted using experimentally obtained parameters revealed qualitatively similar structural and infrared optical temporal evolution with increasing aging time, consistent with the hypothesis that the higher salt concentration accelerated the aging process (Figure ).