Light scattering by large particles – a refinement to the Mean-Field T-matrix method –

Abstract

In the realm of light scattering computational techniques, the T-matrix method serves as a pivotal tool for analysing dust particles composed of aggregated spherical monomers. However, an inherent and significant limitation restricts its application to small aggregates due to the computational demands of processing the translation matrix, whose size becomes prohibitive for aggregates with a large number of spheres. The Mean-Field T-matrix method (MFTM) was proposed as an approximation to address this issue, enabling the treatment of arbitrarily large particles. In the present study, the MFTM method is extended to encompass dust particles that are large, irregular aggregates of polydisperse spherical monomers made from various materials. Additionally, a recently proposed accurate pair correlation function is integrated to describe the spatial distribution of monomers within the aggregate. These advancements render the refined MFTM method both efficient and capable of processing realistic, large dust aggregates. This paper presents a comprehensive application of the enhanced MFTM method to fractal aggregates of spheres with radii following a Schulz distribution. Notably, the refined method is expected to facilitate the derivation of optical properties of atmospheric aerosols and the interpretation of observations from protoplanetary disks.