DDSCAT is a FORTRAN program to calculate scattering and absorption of electromagnetic radiation by arbitrary targets

Version : 5a10

Author(s) : Bruce T. Draine (draine@astro.princeton.edu) , Piotr J.
Flatau (pflatau@ucsd.edu)

License : GPL

Website :
ftp://astro.princeton.edu/draine/scat/ddscat/

Disk space required for installation is 4.05 Mb

The following printable documents will be installed :

- /opt/lfa/doc/DDSCAT.ps
- /opt/lfa/doc/ddscat.ps

DDSCAT is a FORTRAN program to calculate scattering and absorption of

electromagnetic radiation by arbitrary targets using the "Discrete Dipole

Approximation" (DDA). In this approximation the target is replaced by

an array of point dipoles; the electromagnetic scattering problem for the

array of point dipoles is then solved essentially exactly. The DDA was

apparently first proposed by Purcell and Pennypacker (1973). DDA theory is

reviewed and developed further by Draine (1988), Draine and Goodman (1993),

and recently reviewed by Draine and Flatau (1994) and Draine (2000).

DDSCAT.5a10 is a FORTRAN implementation of the DDA developed by the authors.

It is intended to be a versatile implementation, suitable for a wide variety

of applications ranging from interstellar dust to atmospheric aerosols. As

written, the code should be usable for many applications without modification,

but the program is written in a modular form, so that modifications, if

required, should be fairly straightforward. The current version of DDSCAT

uses the DDA formulae from Draine (1988). The code incorporates Fast Fourier

Transform (FFT) methods (Goodman, Draine, and Flatau 1991). The Lattice

Dispersion Relation (LDR) prescription (Draine and Goodman 1993) is used for

determining dipole polarizabilities.

At present the user may choose among different FFT implementations:

(1) FORTRAN implementation (FOURX) from Brenner (1969);

(2) FORTRAN implementation (CFFT99F) from Temperton (1983);

(3) FORTRAN implementation (GPFA) from Temperton (1994);

(4) the native vector library implementation (C3DFFT) on Convex computers.

To facilitate comparisons of the different FFT options, we provide a

separate FORTRAN program TSTFFT which will provide timing information for

comparison of the 3 FORTRAN FFT options. This will enable the user to make

the best choice of FFT for the particular hardware/architecture being used.

The current release of DDSCAT includes an option to calculate torques and

transverse forces on targets, as described in Draine and Weingartner (1996).

Detailed instructions for using DDSCAT are contained in the User Guide for

DDSCAT.5a10.

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