About your unit cell terminology, I prefer "unit cell" and "multi cell" ("supercell" means something else to a crystallographer).
But I also wanted to address a bigger question - how to deal with space group symmetry in order to "fill up" the unit cell. I've seen some discussions about the 230 different space groups and how to incorporate this information into Jmol. If the input file is a SHELXL .res file, all the space group info is present in the "LATT" line and the "SYMM" lines. If LATT is 1, the cell is centrosymmetric (for every atom at x,y,z there is a symmetry related atom at -x,-y,-z); if LATT is -1, the cell is non-centrosymmetric and the space group does not have the -x,-y,-z symmetry operation. The SYMM lines list the other symmetry operations.
Thus, for the popular space group P2(1)/c, the LATT and SYMM lines are:
LATT 1
SYMM -X, .50+Y, .50-ZThe combination of LATT and SYMM in this case, leads to four symmetry-related positions:
x,y,z
-x,-y,-z
-x, 1/2+y, 1/2-z
x, 1/2-y, 1/2+zwhich is all the info needed to "populate" the cell. Of course, depending on the particular co-ordinates, these expressions can lead to molecules in the "next cell over" and it may be necessary to use, e.g., that third symmetry operation as 1-x, 1/2+y, 3/2-z to get the molecule into the central unit cell (it is always legal to add or subtract 1 from the crystal coordinates).
So there is no need to "teach" Jmol about all those space groups!
Pat
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