While the collective optical properties of mixed assemblies generally align with expectations based on linear mixing, cross-coupling between distinct plasmonic particle types gives rise to systematic spectral deviations. MPM offers a clear view of cross-coupling by decomposing spectra intro the contributions of each particle type (Figure ). Without cross-coupling, the average extinction cross-section of each particle should remain constant for all nanocrystal mixing ratios. However, the simulation results demonstrated that as they were diluted by their counterparts, the average extinction cross-section of low-doped particles exhibited a slight redshift, while that of high-doped particles gradually blueshifted.