I am trying to use lammps with periodic boundary conditions for a system with x, y, and z directions oriented normal crystallographic directions  [-1-12] and [-110].
However, the atoms at the ends of the simulation box don't have a perfect coordination number. I tried for fcc metals and the coordination number is less than 12. It works fine if the orientations are .
Could anyone kindly suggest if there is anything wrong I am doing or if there is a way out of this problem.
Here is the part of the script that creates the box and the atoms:
boundary p p p
# create geometry
lattice fcc 3.615 origin 0.0 0.0 0.0 orient x -1 1 0 orient y -1 -1 2 orient z 1 1 1
region box block -30.32 30.32 -27.1 27.1 -3.5 3.5
create_box 1 box
Thanks in advance,