I would like to simulate the textbook example of the woodpile bandgap.
I based my code on the diamond crystal template in the examples
directory, because the woodpile is also arranged on an fcc lattice.
Instead of rectangular rods, I tried this with cylinders because they
are easier to define. The Sozuer paper indicates that these will also
provide a bandgap.
Using mayavi2, when I set the radii to be quite small, the
visualization of the geometry appears correct.
Running the simulation however shows that there is no bandgap. Where
there should be a bandgap, there are quite many modes.
My source is below.
Kind Regards,
Matt
; woodpile lattice ; using diamond lattice from the example files:
; Dielectric spheres in a diamond (fcc) lattice. This file is used in
; the "Data Analysis Tutorial" section of the MPB manual.
(set! geometry-lattice (make lattice
(basis-size (sqrt 0.5) (sqrt 0.5) (sqrt 0.5))
(basis1 0 1 1)
(basis2 1 0 1)
(basis3 1 1 0)))
; Corners of the irreducible Brillouin zone for the fcc lattice,
; in a canonical order:
(set! k-points (interpolate 4 (list
(vector3 0 0.5 0.5) ; X
(vector3 0 0.625 0.375) ; U
(vector3 0 0.5 0) ; L
(vector3 0 0 0) ; Gamma
(vector3 0 0.5 0.5) ; X
(vector3 0.25 0.75 0.5) ; W
(vector3 0.375 0.75 0.375)))) ; K
; define a couple of parameters (which we can set from the command-line)
(define-param eps 13) ; the dielectric constant of the cylinders
(define-param r 0.1) ; the radius of the cylinders
(define si (make dielectric (epsilon eps)))
(set! geometry (list
(make cylinder
(center 0 0 0) (radius r) (axis (vector3 1 1 0))
(height infinity) (material si))
(make cylinder
(center 0 0 (/ 1 4)) (radius r) (axis (vector3 1 -1 0))
(height infinity) (material si))
(make cylinder
(center 0 (/ 1 2) (/ 2 4)) (radius r) (axis (vector3 1 1 0))
(height infinity) (material si))
(make cylinder
(center 0 (/ 1 2) (/ 3 4)) (radius r) (axis (vector3 1 -1 0))
(height infinity) (material si))
))
(set-param! resolution 24)
(set-param! num-bands 10)
(run)
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