i'd like to know what is the number of atoms per unit length for an atomic chain in the [1 1 1] direction of a BCC structure. i can figure out the unit length, however i'm not sure how many atoms to use. Is it 1/8+1/8+1? That means 1/8s for the two corner atoms and 1 atom for the middle? or is it just 3 atoms? part of the problem is i cannot find anywhere the meaning of atomic chain in the BCC structure. likewise, what if i had to find the number of atoms per unit area in the (1 1 1) plane? the area part is easy, but again is the number of atoms 4 or 1/8 * 3 + 1?