Re: anisotrophy

On Mon, 14 May 2007, Aaron Matthews wrote:
> I have tried using the "Matlab's 'contour' function" approach to solve 
> this problem but in every case when i compute the structure in MPB it 
> corrects the lattice directions for a square lattice to the [100] and 
> [010] directions rather than the [1/sqrt2 1/sqrt2 0] and [1/sqrt2 
> -1/sqrt2 0] i assign. I have even tried using a super cell with multiple 
> rods but it still corrects the lattice. Is it possible to override MPB's 
> correction of the lattice directions to visualise an effective 45-degree 
> anisotrophy direction?

MPB does not "correct" the lattice directions; it uses whatever directions 
you specify.

Probably you are being confused by the HDF5 output format: it outputs the 
unit cell of the structure, with an affine grid.  If you plot this in 
Matlab, however, of course Matlab plots everything with a square grid by 
default so the structure will look distorted.

This is covered by the "Data Analysis Tutorial" section of the manual, and 
the solution is to use mpb-data -r to resample the data onto a rectangular 
grid.

Cordially,
Steven G. Johnson