On Sep 2, 2009, at 11:44 PM, ryanhao wrote:
==============================================
but how about the repeated unit takes 2 lattice constant? how
to define the K-path? see attached.
I have tried to decrease the reciprocal lattice to 1/2 of its
previous value, but the result is wrong.
It's hard to answer your question without knowing what your lattice
vectors are.
If your lattice vectors (in geometry-lattice) are orthogonal, with the
first lattice vector oriented along the direction of the waveguide, then
(set! k-points (interpolate 50 (list (vector3 0) (vector3 0.5))))
is correct: the edge of the Brillouin zone is 1/2 of the first
reciprocal lattice vector. (Note that by doubling your period in the
propagation direction, you halve the first reciprocal lattice vector,
halving the size of the Brillouin zone, so the band diagram is
"folded" in two compared to the usual W1 waveguide.)
It's only if you have non-orthogonal lattice vectors that things
become trickier.
Steven
_______________________________________________
mpb-discuss mailing list
[email protected]
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
