ismdust: Extinction due to a power-law distribution of dust grains

This model provides the extinction (= absorption + scattering) properties for a power law distribution of dust grains using the optical properties for dust provided in Draine (2003). The default mixture of 60% / 40% silicate / graphite is described in Corrales et al. (2016). Please cite this paper if you use this model.

The parameters are:

par1	sil_md : dust mass column for silicate (in units of $10^{-4}$)
par2	gra_md : dust mass column for graphite (in units of $10^{-4}$)
par3	redshift : z