Getting negative cross-section for coreshell particle using miepy.cluster()_

[snehaboby]

Hi,

I'm trying to calculate scattering and absorption cross sections for gold-silica core shell nanoparticle dimers. Before jumping to a dimer, I wanted to calculate for a single core shell particle. When I use single_mie_core_shell (from mie_core_shell.py) for a single particle, I get correct positive cross sections. But when I create a core_shell particle and use it with miepy.cluster for just 1 particle, I get negative absorption cross sections and different spectral profile than single_mie_core_shell.
Shouldnt it be the same?
Cluster.py and single_mie_sphere gives same cross_section for just an Au NP. But, its not matching in the case of core-shell particle.

Thank you for your time,