Comparison of radiative transfer Monte Carlo and volume integral equation methods of studying the clustering of small scatterers.

The effect of clustering of small scatterers on optical properties was studied by creation of a Poisson distributed plane-parallel geometry and slow cooling of the particle system in the sense of simulated annealing in an attempt to minimize the assumed total potential energy and sample the spatial distribution during the process. The optical properties were calculated by the volume integral equation method (VIEM). The scattering results for unclustered structures with different size parameters and packing densities were also compared with those given by Monte Carlo simulation for radiative transfer. In particular, measuring the intensity distribution of the VIEM is well suited to the classic radiative transfer approach.