On May 8, 2008, at 2:34 PM, Chris Kang wrote: > My question pertains to the appearance of the bands in the light cone. > While the gap seems to remain intact under the light cone, there seems > to be some states that MPB is calculating that do not appear on the > GME > band plot. Is this merely a difference in how the modes are > calculated, > or is there something wrong with how my structure is set up in MPB? > Any > help would be appreciated.
MPB imposes periodic boundary conditions, so you can't really trust modes above the light line (or at least, you have to interpret them with great care) -- modes above the light line are not confined to the waveguide and therefore "see" the artificial periodicity. (In contrast, modes below the light line are exponentially localized to the waveguide, and the boundary conditions are irrelevant as long as you make the cell size big enough.) If you want to compute leaky modes above the light line, you are best off using some other program. (e.g. our time-domain code, Meep, can do it). Steven _______________________________________________ mpb-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
