Some questions about absorption cross section using HFSS.

Hi ~
I wanna ask some questions about Ansoft HFSS.
Recently i have been using the hfss to calculate a problem about nanoparticle ,we wanna get the scattering and absorption cross section ,we have already get a reasonable result about scattering cross section,but the absorption cross section have not corresponded to the results of other method,such as MIE theory .We use the volume loss density to get the absorption parameter ,but I don't know whether the volume loss density includes the incident fields or not .we got the fields of the particles,it seems not includes the incident field ,just the scattering field.we need to get the total field (incident and scattering fields) of the particles to calculate the absorption .can you tell me the definition of volume loss density (the help doesn't tell me the constituents of volume loss density )? or some advise?
Thanks!

Could you please tell me how to get the scattering cross section of a nano particle?