I think your resolution is way low for this system. as far as I can see your
geometry is 700nm cube
res 32 means your pixel cell size is about 22nm. source is 363nm and in the
dielectric material you use 8 it means wavelength is about 45nm. rule of thumb
is 1 wavelength needs to be represented by 8 pixels, but your 8 pixels makes
176nm about 4 times higher than wavelength.
my suggestion is to use 120resolution minimum to see some meaningful result
comparable to Mie.
Gursoy B. Akguc
________________________________
From: niels jelsma <c.j.m.jel...@student.rug.nl>
To: meep-discuss@ab-initio.mit.edu
Sent: Wednesday, May 29, 2013 2:23 PM
Subject: [Meep-discuss] Resolution dependence silver nanosphere
Dear All,
I'm trying to calculate the dipolemoment of a silver nanosphere in Meep.
In the end I am interested in looking at a chain of spheres and the
transmittance, p_last / p_first.
However for just a single sphere I don't understand what values I have
to choose for the resolution to get proper results.
I've read on the mailing list that I should choose a resolution that
gives at least 8pixels/wavelength and then double the resolution to get
better results.
However, increasing the resolution this way sometimes gives me worse
results.
A simplified version of my script can be found here:
https://gist.github.com/maxnuf/5669273
I've setup a sphere with radius 25nm in 3d space and a continuous source
as plane-wave.
After running it for a while to get into a steady-state I integrate the
Polarization in a volume containing the sphere to find the dipolemoment.
I expect to find a peak near the resonant frequency. So I run the
simulation for several input source wavelengths.
However, for different resolutions, I get completely different results.
I don't know what to do to remedy my problem.
As can be seen in this figure:
http://postimg.org/image/kua54kwq9/
At a resolution 32 I see a sort of dip where I expect the resonant
frequency (which should be at 363nm according to Mie theory)
I'm using Meep 1.2 and a Drude-model for my silver sphere.
How can I determine which resolutions are suitable?
Thanks,
Niels
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