xatom.GaAs.cub8                  | atom.config file
10.6826                          |a0
2.0    0.     0.      1      |real space v(1), and kshif(1)
0.0    2.0    0.      1      |real space v(2), and kshif(2)
0.0    0.0   2.0      1      |real space v(3), and kshif(3)

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v(1),v(2),v(3) xa0 must be lattice vectors of AL(3,3) in atom.config
The reciprocal lattice grid of v(1),v(2),v(3) must have higher symm 
than the system in atom.config
kshift(i)=0, no shift in k-space.
kshift(i)=1, 0.5 reciprocal space shift.

See the directory of Kpt_gen for more explanations.