The discrete dipole approximation (DDA) - is a method for computing scattering of radiation by particles of arbitrary shape. In particle physics, scattering is a class of phenomena by which particles are deflected by collisions with other particles. ...

The discrete-dipole approximation (DDA) is a flexible technique for computing scattering and absorption by targets of arbitrary geometry. Given a target of arbitrary geometry, one seeks to calculate its scattering and absorption properties. Exact solutions to Maxwell's equations are known only for special geometries such as spheres, spheroids, or infinite cylinders, so approximate methods are in general required. The DDA is one such method. Simply stated, the DDA is an approximation of the continuum target by a finite array of polarizable points. The points acquire dipole moments in response to the local electric field. The dipoles of course interact with one another via their electric fields, so the DDA is also sometimes referred to as the coupled dipole approximation. In electromagnetism, Maxwells equations are a set of equations, developed in the latter half of the nineteenth century by James Clerk Maxwell. ... The Earths magnetic field, which is approximately a dipole. ...

This method was originally proposed by E. M. Purcell and C. R. Pennypacker and subsequently developed by B. T. Draine and P. J. Flatau.

References

• Draine, Bruce T., and Flatau, Piotr J. 2003, "User Guide to the Discrete Dipole Approximation Code DDSCAT.6.0", [1].

• Draine, B.T., and P.J. Flatau. Discrete dipole approximation for scattering calculations. J. Opt. Soc. Am. A, 11:1491-1499, 1994. [2]

• E. M. Purcell and C. R. Pennypacker. Scattering and absorption of light by nonspherical dielectric grains. Astrophysical Journal, 186:705, 1973.