Hello everyone, I am using MPB to compute dispersion relations for the diamond lattice as described by a minimal surface equation:
cos(Z) sin(X+Y) + sin(Z) cos(X-Y) = t where X = 2 pi x/a; Y = 2 pi y/a; Z = 2 pi z/a. Lower case x, y and z are the Cartesian coordinates for the surface. The reference for this equation is: Wilts, B.D., Michielsen, K. et al. "Hemispherical brillouin zone imaging of a diamond-type biological photonic crystal", J. R. Soc. Interface, doi:10.1098/rsif.2011.0730. I am attempting to compare the band results for this surface with those of a regular diamond lattice at the same dielectric filling fraction, 78.5 %. The band diagrams compare favorably but are not the same. I am unsure (due to lack of experience) as to whether or not I have set the calculation up correctly. The iso-surface plot produced by rote calculation of the surface looks different than the iso-surface plot produced by viewing the epsilon.h5 file by using Visit. My ctl file is shown below. Any help will be appreciated. Thanks very much. ; diamond lattice - surface equation method test ; (define pi 3.141592654) (define a 1.0) (define twopioa (/ (* 2 pi) a)) (define px 0.0) (define py 0.0) (define pz 0.0) (define fr 0.0) (define t 0.70) (define epsc 2.45) (define epsa 1.0) (define (eps-func p) (set! fr 0.0) (set! px (vector3-x (lattice->cartesian p))) (set! py (vector3-y (lattice->cartesian p))) (set! pz (vector3-z (lattice->cartesian p))) (set! fr (+ (+ (* px twopioa) (* py twopioa)) (* pz twopioa))) (make dielectric (epsilon (if (> fr t) epsa epsc )))) (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))) (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 (set! default-material (make material-function (material-func eps-func))) (set-param! resolution 32) (set-param! mesh-size 3) (set-param! num-bands 3) (run) Doug Nance _______________________________________________ mpb-discuss mailing list mpb-discuss@ab-initio.mit.edu http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss