Simulation of nanocrystal gels. Brownian dynamics simulations were performed in HOOMD-blue (v2.9.7) with N = 64000 spherical nanoparticles of mean thermodynamic radius a = 7.32 nm, polydispersity of 0.10a, and volume fraction of η = 0.01 in a triply-periodic box with an integration time step of ∆t = 10 -4 τ D , where τ D = γ H a 2 /k B T is the diffusion time in terms of the hydrodynamic drag coefficient γ H . Nanoparticles interacted with hard sphere repulsions and short-ranged attractions of approximate range 0.1a and contact strength 10k B T . Three MPM simulations for each sampled configuration were performed to find the polarization-averaged extinction cross-section using an optical radius of 5.9 nm for all nanoparticles and a core-shell Drude dielectric function described in Table . The extinction spectra were normalized by dividing by their maximum values.