Plotting a crystal in Mathcad

Hello guys,

I have a question about ploting a crystal in Mathcad. In general crystal is made by translation of unit cell in a periodical way along x,y,z for some increment a, b, c. The a, b and c determine the size of unit cell, while x, y and z can be at some angle: alpha, beta, gamma (see attached figure).

Lets say that crystal is rock salt (NaCl). Then Na and Cl atoms are positioned within unit cell in some regular manner. The plotting of one unit cell in a form of 3D plot in Mathcad is simple, but I am curious how to create a crystal of desired size? I guess it has to do something with vectors.

Thanks,

Goran

NaCl unit cell                                        NaCl crystal - 3x3 unit cells