Hello Dr.Steven and MPB-users, For the first line of my below ctl file, if I use a supercell-y of different length than a multiply of (sqrt 3) I get a wrong picture of the triangular lattice epsilon image. Why? How can I get the attached image file (4 holes sidelong of line defect) by using a rectangular cell ? What supercell-y, geometry-lattice size and geometric-objects-lattice-duplicates multiplies do you suggest?
My second question is that does mpb allows us to define the geometry via two
cases? With an if statement isn't is possible? (For the calculation of extended
states and guided modes two different geometries can be used. )
Thank you for your kind consideration.
Regards,
Fulya Bagci
Ankara University,
Dep.of Eng. Physics.
-----------------------------------------------------
;This is a PhC slab waveguide, formed from triangular lattice of air holes in a
silicon slab, suspended in air---PhCs: Molding the Flow of Light, chapter 8,
fig.8
;--define parameters
;??(define-param supercell-y 7)
(define-param supercell-y (* 3 (sqrt 3)))
(define-param eps 12) ;die. constant of slab
(define-param r 0.3) ,radius of holes
(define-param h 0.6) ;thickness of slab
(define-param supercell-h 4) ;thickness of slab+air surround to calculate
index-guided ;modes
(define matsi (make dielectric (epsilon 12)))
;--set geometry-lattice
(set! geometry-lattice (make lattice (size 1 supercell-y supercell-h)))
;--set geometry dublicate geometry
(set! geometry (list
(make block (material air)(center 0)(size infinity infinity supercell-h))
(make block (material matsi)(center 0)(size infinity infinity h)) ))
;-----
(set! geometry
(append geometry
(geometric-objects-lattice-duplicates
(list
(make cylinder (center 0 0 0) (radius r) (height h)
(material air))) 1 (sqrt 3) supercell-h)
))
(set! geometry
(append geometry
(geometric-objects-lattice-duplicates
(list
(make cylinder (center -0.5 -0.866 0)(radius r) (height h)
(material air))) 1 (sqrt 3) supercell-h)
))
; add a line-defect
(set! geometry (append geometry (list (make cylinder (center 0 0 0)(radius
r)(height h)(material matsi) ) ) ))
(set-param! resolution (vector3 32 32 16))
;--set k-points
(define Gamma (vector3 0.3 0 0))
(define K' (lattice->reciprocal (vector3 0.5 0 0))) ; edge of Brillouin zone.
(set! k-points (interpolate 13 (list Gamma K')))
(set! tolerance 1e-3)
;--run
(define-param extra-bands 15)
(set! num-bands (+ 5 extra-bands))
(run-yeven-zeven)
(run-yodd-zeven)
triaindielectricwaveguide
Description: Binary data
_______________________________________________ mpb-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
