Hi Michael,
OptiFDTD can model material absorption through complex refractive indices. Scatting is done simply from the geometry of the particles in the material. However, I believe you are referring to the coefficients that are based off of scattering/absorption cross-sections which is not an input into the simulation engine as it would need the direct material properties (macro versus micro). Is my assessment of what you are looking for correct? Could you provide more details or an example of what you are looking for.
You could use the product to determine the absorption and scattering coefficients.
Scott