Question on supercell, and coordination

Dear Mr. Johnson and MPB users

I intend to simulate the dispersion diagram of coupled cavity located beside a line defect of the air holes on the epsilon. like below:
o= holes
x= defect
ooooooooooooooooooo....
ooooxooooxooooxoooo....
ooooooooooooooooooo....
xxxxxxxxxxxxxxxxxxxxx....
ooooooooooooooooooo....
ooooooooooooooooooo....
ooooooooooooooooooo...

My questions:
1- it seems I have to define the supercell with the (size 5 7 nosize). and remove 5 holes from middle (to make a waveguide) and one from upper line(to make a point defect, (as it is clear in my ctl attached file) it will be OK. is it correct?

2-if I define supercell (size 10 7 nosize), and remove 10 holes from middle (to make a waveguide) and two from upper line with (to make two point defects with 4 a far from each other, (as it is clear in my second ctl attached file) the dispersion curves should be same as previous one, but they are different!! why?

3- if I want to modify ctl file for triangular lattice, are the modification on (basis1 (/ (sqrt 3) 2) 0.5)  and   (basis2 (/ (sqrt 3) 2) -0.5) enough or I have to modify any other part of ctl file? (unfortunately every time I confuse between the coordination systems lattice, Cartesian , .... )


 
regards
Hassan

==============
;first ctl file, 5*7

(set! default-material (make dielectric (epsilon 12)))
(define Gamma' (vector3 0 0 0))
(define K' (lattice->reciprocal (vector3 0.5 0 0))) ; edge of Brillouin zone.
(set! k-points (interpolate 4 (list Gamma' K')))
(set! num-bands 10)
(set-param! resolution 32)

(set! geometry-lattice (make lattice 
             (size 5 7 no-size)))
(set! geometry (list (make cylinder
               (center 0 0 0) (radius r) (height infinity)
            (material air))))
(set! geometry 
        (append
            (geometric-objects-lattice-duplicates geometry)
            (list ; add a row of rods (epsilon) on Center, to make a waveguide:
                (make cylinder (center -2 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center -1 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  0 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  1 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  2 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                
                ; add a rod (epsilon) on _-2 -2 0), to make a cavity:
                (make cylinder (center -2 -2  0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
            )))


(run-te)


==================================
; second ctl, super cell (10*7)

(set! default-material (make dielectric (epsilon 12)))
(define Gamma' (vector3 0 0 0))
(define K' (lattice->reciprocal (vector3 0.5 0 0))) ; edge of Brillouin zone.
(set! k-points (interpolate 4 (list Gamma' K')))
(set! num-bands 10)
(set-param! resolution 32)

(set! geometry-lattice (make lattice 
             (size 10 7  no-size)))
(set! geometry (list (make cylinder
               (center 0 0 0) (radius r) (height infinity)
            (material air))))
(set! geometry 
        (append
            (geometric-objects-lattice-duplicates geometry)
            (list ; add a row of rods (epsilon) on Center, to make a waveguide:

                (make cylinder (center -5 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center -4 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center -3 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center -2 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center -1 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  0 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  1 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  2 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  3 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  4 0 0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                ; add two rod (epsilon) on _-5 -2 0 and 0 -2 0 , to make a cavity:
                (make cylinder (center -5 -2  0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
                (make cylinder (center  0 -2  0) (radius r) (height infinity) (material (make dielectric (epsilon eps)))
            )))


(run-te)

_______________________________________________
mpb-discuss mailing list
[email protected]
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss