On May 12, 2010, at 7:21 AM, Ad Khan wrote:
I am trying to simulate a metallic nanosphere. I have seen a method in the meep's manual that how to model a dispersive material. I have also seen the example of the material dispersion. But the problem is that i don't know how to calculate the parameters i.e. omega, gamma and sigma. Please somebody help me in this regard.
This is a nonlinear fitting problem. Take the experimental data (or whatever) that you want to fit, choose the bandwidth that you care about, and then do a fit (e.g. least-squares) of one or more Lorentzians to this data. There is lots of fitting software on the web that you can try.
(You can also try our NLopt nonlinear optimization library, if you want to whack this problem with a general optimization approach: http://ab-initio.mit.edu/nlopt)
(Technically this specific fitting problem is equivalent to IIR filter design, and you can find lots of references under that name.)
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