Disordered states from Brownian dynamics. We use Brownian dynamics to simulate up to N = 8000 model plasmonic nanoparticles that mutually interact by a pairwise potential comprising a hard-sphere repulsion and an isotropic, short-ranged attraction of strength U 0 and range δ = 0.1a (see eq (8)). All simulations are initialized from particles in random positions and advanced for sufficient time steps to attain an equilibrated or long-lived arrested state. Particle configurations are collected for analysis via MPM from the resulting terminal macrostates, the nature of which depends on the nanoparticle volume fraction η and the ratio of attraction strength U 0 to the thermal energy scale k B T , where k B is the Boltzmann constant, and T is temperature. For volume fractions in the range 0 ≤ η ≤ 0.50, we generate equilibrium colloidal fluid macrostates with 0 ≤ U 0 /k B T ≤ 3 and gel-like structures in an arrested fluid-crystal phase separation region at U 0 /k B T = 10.