Hello MPB users,
To add on to Rafael's query I had problems in matching results of a paper
which does calculations using plane wave expansion method itself. I had
posted my query and is in archive unanswered till now :(
http://www.mail-archive.com/mpb-discuss@ab-initio.mit.edu/msg00854.html
I am copying my same query here as well:
I tried to reproduce the band-diagram results of a famous paper from *M*. *
Notomi* : *Phys*. *Rev*. *B* 62, 10696 (*2000*)
In this paper figure 7(b) shows a band-diagram of hexagonal pillars of GaAs
(n = 3.6) rods of radius 0.35a in air (n = 1).
It was very easy to modify the mpb example tri-rods.ctl to do the same
diagram. I tried but could not match the band diagram as given in the paper
!
Appearance wise both results look very similar on first hand but closer
inspection shows the difference.
In the paper e.g. band 5 goes from frequency value 0.56 to *0.635* (as
explicitly mentioned in explanation of Fig. 6 in the same paper) but in my
calculated values using mpb i get them in the range 0.56 - *0.615* (the
upper frequency value doesn't match).
As far as i know the results of said paper were not calculated using mpb
then is this discrepancy arising because of that ? If so, then how to make
sure which result is more accurate ?
I'm just putting my .ctl file below for all to have a look and suggest if i
made any mistake in setting up .ctl file itself or i'm missing out on
something which may improve my result.
Any help in this will be much appreciated.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(set! num-bands 8)
(set! geometry-lattice (make lattice (size 1 1 no-size)
(basis1 (/ (sqrt 3) 2) 0.5)
(basis2 (/ (sqrt 3) 2) -0.5)))
(set! geometry (list (make cylinder
(center 0 0 0) (radius 0.35) (height infinity)
(material (make dielectric (epsilon 12.96))))))
(set! k-points (list
(vector3 (/ -3) (/ 3) 0) ; K
(vector3 0 0.5 0) ; M
(vector3 0 0 0) ; Gamma
(vector3 (/ -3) (/ 3) 0) ; K
))
(set! k-points (interpolate 4 k-points))
(set! resolution 64)
(run-te)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
On 11 August 2012 05:18, Rafael Gonzalez <rafael.g...@gmail.com> wrote:
> Hello
>
> I'm trying to reproduce a paper on bandgaps for 2D lattices. These
> authors report using a FEM method. I understand this approach is
> different from the one that MPB uses. And so are the results. I get
> very similar in shape dispersion diagrams but the bandgaps reported by
> them are completely different. I thought it could be provoked for ther
> lack of resolution of the simulation I ran, but the same results were
> obtained. I also changed the cell size for the averaging and the block
> size of the eigen solver but none of these parameters seemed to be the
> reason of the discrepancy. I also thought it could be the difference
> of the approaches to solve the eigenvalue problem, but I guess that a
> given geometry must have a unique dispersion diagram. Numeric errors
> are to be expected but I guess either one of us is doing something
> wrong. Anyone has any clue?
>
> Best regards
>
> _______________________________________________
> mpb-discuss mailing list
> mpb-discuss@ab-initio.mit.edu
> http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
>
--
...................................................................
Regards,
manish
http://web.iitd.ernet.in/~phz118136/
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