The dhkl is the perpendicular distance from. d-spacing :can be defined as the spacing between successive (hkl) planes ,and about the question of atoms and particles ,as we know that the logical relation of Crystal structure ( lattice+basis=Crystal structure) , and according to definition of basis (when basis of atoms attached identically to each lattice point ,. Miller indices form a notation system in crystallography for planes in crystal ( Bravais) lattices. Inter-Planar Spacing, dhkl, and Miller Indices. Ex: An element, BCC or FCC, shows diffraction peaks at 2θ: 40, 58, 73, 86.