Dear Steven, Thanks a lot for your detailed explanation on the dielectric constant stuff in MPB. It really solved my puzzle. I have another quick question here if you don't mind. Since MPB uses the same grid for E and H field, how does it actually calculate the derivatives? Suppose it wants to know the curl of H field at point A, does it just calculate the differences between its neighboring points and then divide by 2dr? In addition, is the output tensor epsilon_inverse the same one used by MPB internally to solve H field, while epsilon the one used for E field?
Best regards, Minghui Han On 10/2/06 4:27 PM, "Steven G. Johnson" <[EMAIL PROTECTED]> wrote: > On Sun, 1 Oct 2006, Minghui Han wrote: >> Thanks Steve. I actually already tried to output both E and D, but then >> the epsilon inferred from D/E varies for different Bloch modes. Since >> what I want is the actual epsilon for Ex and Ey used in MPB, and I also >> want it to be the same for all Bloch modes for a given structure, do you >> think it is possible to implement the smoothing method externally by >> myself, just following what is described in your MPB paper and Meade's >> 93 paper? > > First off, I should apologize - I confused this with the Meep mailing > list, so I mis-answered your question. MPB does indeed output the full > dielectric tensor: do an 'h5ls' on epsilon.h5 and you will see all of the > tensor components. Also, there is no Yee grid or interpolation in MPB, so > this is not an issue. > > Second of all, you are inferring epsilon incorrectly if you think it is > different for different Bloch modes. MPB (and Meep) uses the same epsilon > tensor regardless of the field pattern. You're perhaps confused by the > fact that epsilon is a *tensor*, so you can't infer it merely by dividing > D/E. (You need 3 D's and 3 E's at a given point to infer the tensor.) > > It is certainly possible to implement the smoothing method by yourself, > but it shouldn't be necessary. > > Steven _______________________________________________ mpb-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
