Hi Steven, MPB users, Below is a simple program performing 3D calculations of an air-bridge H1 cavity (one missing hole). When using supercell-size 2 sz=2, one finds the main mode at band 26 (see attachment). Using sz=3 the mode is now located at band 35, increasing sz further shifts the main mode to higher order bands. Considering that band folding is not affected by the supercell size in the out-of-plane direction (non periodic) how can the appearance of additional bands be explained? and if possible, can the position of the main mode be predicted as a function of sz? I have tried increasing the resolution, using different k-point...without solving that issue. Any suggestions?
Thanks,
Fred
; A triangular lattice of air holes with H1 defect
(define-param sx 5)
(define-param sy 5)
(define-param sz 2)
(define-param resxy 16)
(define-param resz 10)
(define-param bands 50)
(define r 0.36)
(define h 0.75)
(define eps 8.4)
(set! mesh-size 6)
(set! num-bands bands)
(define Gamma (vector3 0))
(define M0 (vector3 0 0.5 0))
(define K0 (vector3 (/ -3) (/ 3) 0))
(set! geometry-lattice (make lattice (size sx sy sz)
(basis1 (/ (sqrt 3) 2) 0.5)
(basis2 (/ (sqrt 3) 2) -0.5)))
(set! geometry (list (make block (material air)
(center 0)
(size infinity infinity infinity))
(make block (material (make dielectric (epsilon eps)))
(center 0)
(size infinity infinity h))))
(set! geometry (append geometry (geometric-objects-lattice-duplicates (list
(make cylinder
(center 0) (radius r) (height infinity)
(material air))))))
(set! geometry (append geometry
(list (make cylinder
(center 0) (radius r) (height h)
(material (make dielectric (epsilon eps)))))))
(set! k-points (list M0))
(set! resolution (vector3 resxy resxy resz))
(set! tolerance 1e-5) (run-zeven) (output-dpwr bands) -- Frederic Brossard Hitachi Cambridge Laboratory Cavendish Laboratory J J Thomson Avenue Cambridge CB3 0HE
<<attachment: 3DH1b26.png>>
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