[Wien] WZ structure (Band Gap problem)

[U P Verma]

Respected Ahmed ji

I have calculated the electronic structure of WZ AlN using
lattice co-ordinate


Al
0.333333 0.66666666 0.000000
0.666666  0.3333333 0.500000

N
0.33333  0.666666  0.384000
0.66666  0.333333  0.884800

But I have a problem with band structure

(1) splitting of energy near fermi energy level
(2) Structure parameter B prime is too low 0.9450
but the value of the bulk modulus is close to Exp.

Help me
Thanks in advance
P S Bisht