On Nov 24, 2009, at 3:15 PM, JiangjunZheng wrote:
The half of the modes I means that by using the rectangular lattice, the number of the waveguide modes is smaller than that by using triangular lattices. Could you please help me checking the following codes? It uses the rectangular lattice. It should be very simple for you. For W1, the results are different for the triangular and rectangular lattices, too.
For one thing, you don't say what your triangular lattice code looks like; maybe you have bugs there. You also don't say how you are counting waveguide modes.
For another thing, remember that the boundary conditions are periodic. If you take your structure and imagine repeating it periodically in the lateral directions, you'll see that the two lateral sides of your unit cell don't match up. This means that you effectively have an additional line defect at the edge of your rectangular supercell, which is not what you want. You need to add another half a period to each side in the lateral direction to make them match.
Steven _______________________________________________ mpb-discuss mailing list mpb-discuss@ab-initio.mit.edu http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
