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; 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 11.56) ; the dielectric constant of the spheres
(define-param r 0.25) ; the radius of the spheres
(define diel (make dielectric (epsilon eps)))
; A diamond lattice has two "atoms" per unit cell:
(set! geometry (list (make sphere (center 0.125 0.125 0.125) (radius r)
(material diel))
(make sphere (center -0.125 -0.125 -0.125) (radius r)
(material diel))))
; (A simple fcc lattice would have only one sphere/object at the origin.)
(set-param! resolution 16) ; use a 16x16x16 grid
(set-param! mesh-size 5)
(set-param! num-bands 5)
; run calculation, outputting electric-field energy density at the U point:
(run (output-at-kpoint (vector3 0 0.625 0.375) output-dpwr))
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