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DDSCAT: The Discrete Dipole Approximation for Scattering and
Absorption of Light by Irregular Particles
B. T. Draine1 &
Piotr J. Flatau2
1Dept. of Astrophysical Sciences, Princeton University
2Scripps Institution, UCSD
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.
Subject headings: ISM: dust, ISM: extinction, radiative transfer,
scattering
Latest Version: DDSCAT.5a10 (2000 August 9)
Archived: 2000 August 14
Papers: (multiple, representative):
Draine, B. T. & Weingartner, Joseph C., 1996ApJ...470..551D
Draine, B. T. & Flatau, P. J. 2000, astro-ph/0008151
Language: Fortran
Source Code (ASCL archived):
ddscat5a10.tar.gz
Source Code (latest):
http://astro.princeton.edu/~draine/DDSCAT.html