  Bright, saturated structural colors in birds have inspired synthesis of
self-assembled, disordered arrays of assembled nanoparticles with varied
particle spacings and refractive indices. However, predicting colors of
assembled nanoparticles, and thereby guiding their synthesis, remains
challenging due to the effects of multiple scattering and strong absorption.
Here, we use a computational approach to first reconstruct the nanoparticles'
assembled structures from small-angle scattering measurements and then input
the reconstructed structures to a finite-difference time-domain method to
predict their color and reflectance. This computational approach is
successfully validated by comparing its predictions against experimentally
measured reflectance and provides a pathway for reverse engineering colloidal
assemblies with desired optical and photothermal properties.
