Question about the irreducible Brillouin zone of a triangular lattice in MPB

Dear All,

          I find a question about the irreducible Brillouin zone of a
triangular lattice in MPB.
          In the MPB manual, it give a example  for the irreducible
Brillouin zone of a triangular lattice :
set! k-points (list (vector3 0 0 0)          ; Gamma
                     (vector3 0 0.5 0)        ; M
                     (vector3 (/ -3) (/ 3) 0) ; K
                     (vector3 0 0 0)))        ; Gamma
(set! k-points (interpolate 4 k-points))

I am confused at the value of  K point!
I think the value of K point should be  (vector3 (/ 0.5 sqrt(3))
0.50).please see the picture attached.
Why Steven put  (vector3 (/ -3) (/ 3) 0) here?

   0, 0.5

0.5/sqrt3, 0.5

Gamma

0, 0

M

K

-- 
===========================================

Best wishes

                      Yours,
                      Ryan Hao



Wuhan National Laboratory for Optoelectronics
Institute of Optoelectronic Sinence and Engineering, HUST University
Wuhan, 430074, P.R.CHINA
Phone: 86-027-87792242-809(O)
Mobile:
Fax:

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