Re: Outputting field profiles

On Tue, 30 May 2006, Melanie Ayre wrote:
> I am using mpb to calculate the field profiles of a W1 supercell, and am 
> having difficulty with the output.  To get enough of the dispersion diagram, 
> I usually calculate the first 50 or so bands, and I want to output E, D, and 
> H for say the last ten bands.
>
> To do this, I put
>
> (run
> fix-hfield-phase
> (get-efield 40)
> (output-efield 40)
> )

This is a common misunderstanding.  The band functions need to be 
*functions* that are passed to run.  When you pass (get-efield 40), you 
are passing the *result* of *calling* (get-efield 40), and not a function. 
This results in an error because it means that you are calling get-efield 
before computing the fields with (run).

Also, output-efield calls get-efield; you don't need both.

Instead, what you want is to define a new band function which only calls 
output-efield for the last ten bands.

(define (output-some-efields b)
    (if (>= b (- num-bands 10))
       (output-efield b)))

(run output-some-efields)