Packing two unit cells of NaCl

Start Oscail and use to point to nacl.ins. The file should be in \ortex.

Click to start ORTEX.

To Use Defaults ? answer NO and 
then answer Yes to Use Covalent Radii for Bonds ?
select Add Unit Cell on the ORTEX Options dialog and OK.

Click to go to atom mode, click to start lattice pack.

select Lattice Pack with Limits and click OK.

Set the X-Range limits to 0 and 2 on the pack range dialog

and click OK.

You now have two packed unit cells.
To examine the symmetry properties of any ion click to return to LINE MODE
and click to go to LINE MODE EDIT

Click any ion to select it and click to get the symmop on the status bar (in this case 65527).