the results from the @Weingartner2001a model for a wide range of grain sizes (between 5 Å and 0.1 $\mu$m), and using various choices for the incident radiation field. A detailed discussion of this comparison can be found in @VanHoof2001.

We include an embedded model for Mie scattering [@Mie1908], which uses refractive index data for each material type. It is based on the code described in @Hansen1974 and was later modified by P.G. Martin. New grain materials can be included by specifying the relevant refractive index data or by supplying opacity tables. The user specifies the size-distribution function and the number of grain size bins. A number of size-distribution functions are available as built-in functions, including the ones described in @Mathis1977 [hereafter MRN], @BFM, and @Abel2008.  will then “compile” the grain data to create scattering and absorption cross sections, the scattering asymmetry factor, and the inverse attenuation length for each material type and grain size as a function of frequency. A number of pre-compiled grain types are included in the code distribution.

In practice, it is difficult to introduce new grain materials because of the wavelength range considered by the code. Laboratory data can extend from the IR into the UV, 