Hi,
I am trying to get scattering cross-section from gold hemispherical nanoparticle (r = 20 nm) placed on the Silicon substrate. I am attaching my image of the geometry. Substrate is being modeled by a cylindrical domain inside air domain. The issue is I am not getting plasmonic resonance and just getting noise. I am aware of the "scattering from the substrate" model on COMSOL. However, I wanted to solve for scattering field instead of total field. And I think instead of representing entire lower half by the substrate, it could be represented by a slab too? What are your suggestions?
Regards,
Hamza
Dear Hamza,
may I ask how coarse is your mesh? If I need to bet on what is the problem I would say that very likely your mesh is very coarse and you cannot resolve with accuracy your simulation. Try to perform a h-refinement (mesh convergence study) to see if with finner meshes you get an asymptotic output.
Kind regards,
Julian
Dear Julian,
Thanks for your reply.
In the absence of scatterer I do get resonance (figure attached). So i believed meshing might not be the issue as there should be some resonant behavior.
I was wondering if using scattering field formulation is the source of problem?
But I will try what you are suggesting, can you tell me how to do mesh convergence study. My system has just 16 GB of RAM, I wonder if that will be a bottleneck?
I am setting global size of mesh to finer. The meshing of nanoparticle and substrate domain is set to extra fine.
Regards
Hamza
Hi J. Anaya . I edited the meshing to have atleast 6 elements per wavelength, but still there is no change in the results, any suggestions?
Dear Hamza,
It is very interesting that you are getting the strange behavior only when using the scattered field formulation. May I ask what are you using as background electric field? If you do not have that clear I would use the full field formulation --both are identical, but the scattered field separates the problem in the superposition both: Total field= Background field + scattered field. If you are not giving the right background field that can be the root cause of your problem.
Kind regards,
Julian
Sir J. Anaya . I am defining it as: E0*exp(-j*emw.k0*x) ..polarized in z direction.
I understand you must be busy, but I am gonna stretch my luck. I am inboxing you my file on your inbox, if you would be kind enough to see if I am making any bloopers.
Regards,
Hamza
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