Hi, I have been trying all sort of un-satisfying changes to my ctl file
to try to use a rectangular epsilon file without success. If someone is
familiar with this, I would greatly appreciate your help.
What I am doing:
I run the diamond.ctl file from the examples folder of mpb.
I then run the command: mpb-data -r -o eps-r.h5 epsilon.h5 ; this
creates a second file with rectangular axis.
I then try to re-read this file with a slightly modified diamond.ctl
file and run mpb to, hopefully, obtain the same bands.
The problem is whatever I try, I always get the error:
...
Solving for band polarization: .
Initializing fields to random numbers...
ERROR: non positive-definite dielectric tensor
CHECK failure on line 421 of mpb.c: invalid dielectric function
I have been trying modifications of the type cartesian->lattice,
lattice->cartesian on the basis set without success.
Here's the modified ctl file if that helps:
; Dielectric spheres in a diamond (fcc) lattice. This file is used in
; the "Data Analysis Tutorial" section of the MPB manual.
(set! geometry-lattice (make lattice
(basis-size (sqrt 0.5) (sqrt 0.5) (sqrt 0.5))
(basis1 (lattice->cartesian (vector3 1 0 0)))
(basis2 (lattice->cartesian (vector3 0 1 0)))
(basis3 (lattice->cartesian (vector3 0 0 1)))))
(set! epsilon-input-file "eps-r.h5")
; Corners of the irreducible Brillouin zone for the fcc lattice,
; in a canonical order:
(set! k-points (interpolate 4 (list
(vector3 0 0 0) ; Gamma
(vector3 0.375 0.75 0.375)))) ; K
; define a couple of parameters (which we can set from the command-line)
(define-param eps 11.56) ; the dielectric constant of the spheres
(define-param r 0.25) ; the radius of the spheres
(define diel (make dielectric (epsilon eps)))
;; A diamond lattice has two "atoms" per unit cell:
;(set! geometry (list (make sphere (center 0.125 0.125 0.125) (radius
r)
; (material diel))
; (make sphere (center -0.125 -0.125 -0.125) (radius r)
; (material diel))))
; (A simple fcc lattice would have only one sphere/object at the
origin.)
(set-param! resolution 16) ; use a 16x16x16 grid
(set-param! mesh-size 1)
(set-param! num-bands 5)
; run calculation, outputting electric-field energy density at the U
point:
(run)
Please help!
Nic
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