Dear MEEP users,
I get a Drude model for Au (the model itself has been proved to be accurate
with applicable wavelength range: 500~1000nm), and want to verify it through
simulaltion as the MEEP Tutorial of Material dispersion. I made a slight
change to the given tutorial .ctl file. However, the result achieved is not
what I have expected. The .ctl command and partial simulation results are as
follows. Any statement about my problem will be highly appreciated.
With best regards.
***************************************
The ctl command:
; Define lengthscale a = 200nm
; Wavelength range : 500~1000nm
; Corresponding frequency range in MEEP : 0.2 ~ 0.4
(set! geometry-lattice (make lattice (size no-size no-size no-size)))
(set-param! resolution 20)
(set! default-material
(make dielectric (epsilon 5.9673)
(E-polarizations
(make polarizability (omega 0.666667e-10) (gamma 0.0106133)
(sigma 4.4673e20))
(make polarizability (omega 0.43338) (gamma 0.0699067) (sigma
1.09))
)
)
)
(define-param fcen 0.3)
(define-param df 0.2)
(set! sources (list (make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Ez) (center 0 0 0))))
(define-param kmin 0.2)
(define-param kmax 0.4) ; I am not sure if the values for kmin
and kmax are right. However, even if I change these values, the results and
the problem are the same.
(define-param k-interp 99)
(define kpts (interpolate k-interp (list (vector3 kmin) (vector3 kmax))))
(define all-freqs (run-k-points 200 kpts)) ; a list of lists of frequencies
(map
(lambda (kx fs)
(map
(lambda (f) (print "eps:, " (real-part f) ", " (imag-part f) ",
" (sqr (/ kx f)) "\n"))
fs
)
)
(map vector3-x kpts) all-freqs
)
*********************************
Partial simulation results:
...
harminv0:, frequency, imag. freq., Q, |amp|, amplitude, error
run 0 finished at t = 250.0 (10000 timesteps)
freqs:, 1, 0.2, 0, 0
freqs-im:, 1, 0.2, 0, 0
harminv1:, frequency, imag. freq., Q, |amp|, amplitude, error
run 1 finished at t = 250.0 (10000 timesteps)
freqs:, 2, 0.202, 0, 0
freqs-im:, 2, 0.202, 0, 0
...
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