Some Representative Crystal Structures
This Demonstration is a tool for the visualization of crystal structures, showing either the unit cell or a periodic repetition. You can also add periodically duplicate atoms at the cell edges, which means that atoms located close to the cell boundaries are copied to the opposite side (where the next atom of the same type would be in a periodic solid). You can choose a variety of layout choices for atoms, bonds, cell outlines, and arrows. For a wireframe plot, set all atom radii to 0; to disable bonds, set the maximum bond distance to 0. The cell outlines and arrows can be manipulated to show the unit cell or the periodically repeated supercell.
Crystal structure data taken from , provided by the Center for Computational Materials Science of the United States Naval Research Laboratory.
 "Crystal Lattice Structures." United States Naval Research Laboratory. (Oct 29, 2008) cst-www.nrl.navy.mil/lattice/index.html.
For NaCl, two different cells have been included in this Demonstration. The cell denoted as "primitive" is the smallest unit cell you can find for the crystal, but the cubic representation is far more common in literature.