User Guide for the Discrete Dipole Approximation Code DDSCAT (Version 5a10)

TL;DR

DDSCAT.5a10 is a portable Fortran software that uses the discrete dipole approximation to accurately compute electromagnetic scattering and absorption for targets with complex geometries and material properties, within specified size and refractive index limits.

Contribution

This paper provides a comprehensive user guide for DDSCAT.5a10, detailing its capabilities, target geometries, and how to perform electromagnetic scattering calculations with the software.

Findings

Supports a variety of target geometries

Calculates total cross sections and Mueller matrix elements

Handles inhomogeneous and anisotropic materials

Abstract

DDSCAT.5a is a freely available software package which applies the "discrete dipole approximation" (DDA) to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The DDA approximates the target by an array of polarizable points. DDSCAT.5a requires that these polarizable points be located on a cubic lattice. DDSCAT.5a10 allows accurate calculations of electromagnetic scattering from targets with "size parameters" 2 pi a/lambda < 15 provided the refractive index m is not large compared to unity (|m-1| < 1). The DDSCAT package is written in Fortran and is highly portable. The program supports calculations for a variety of target geometries (e.g., ellipsoids, regular tetrahedra, rectangular solids, finite cylinders, hexagonal prisms, etc.). Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to import arbitrary target geometries into the code, and relatively straightforward to add new target generation capability to the package. DDSCAT automatically calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix for specified orientation of the target relative to the incident wave, and for specified scattering directions. This User Guide explains how to use DDSCAT.5a10 to carry out EM scattering calculations. CPU and memory requirements are described.