Re: need your help above woodpile calcalation

On Tue, 21 Nov 2006, Rong-Tai Hong wrote:
>    I¡¦m trying to use MPB to calculate the band structure of ¡§woodpile¡¨
> photonic crystals recently. There is no problem of the result when I use a
> FCC lattice. But when I change the height of stacked logs to make a FCT
> structure, the calculated results is incorrect comparing to FDTD
> transmission spectrum. There is always bandgap at higher frequency range
> than the actual one. The geometry of my structure is w=0.25a, h=0.25a,
> eps=10.3684. My code is shown as the following:

Your k points are wrong, I think.

The coordinates of the Brillouin zone corners change when you distort the 
lattice from fcc to fct.  I don't know what the new coordinates are; 
you'll have to look them up or work them out.

You also aren't using enough k-points.  The irreducible Brillouin zone is 
larger than that of fcc because of the broken symmetry.  This is true even 
for the fcc woodpile, because the woodpile structure breaks some of the 
fcc symmetry (the irreducible Brillouin zone is determined by the symmetry 
group of the *structure*, not the symmetry of the *lattice*).

Steven

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