Step 3 - Set up a Configuration
To create our silica configuration we’ll use the “relative random mix” generator as a basis.
Configuration ⇨ Create…
Choose both species and press
Leave the configuration type as Mixture and press
Leave the box style as Fixed Geometry, Undefined Size but set the angle γ to
120degrees (this will give us a monoclinic box) and press
Now we need to set up a relative mix of our two species:
In the table change the Population / Ratio of oxygen from
1to2
Set the Density of the box to
0.066- note that this is in units of atoms Å-3
Set the Multiplier to
1500
Press to complete the wizard.
Double-click on the configuration tab’s title and change its name to
Bulk
Note that We use units of atoms Å-3 here as this allows us to add both atomic components using the same density value. If we had chosen units of g cm-3 we would have to know the individual densities of silicon and oxygen in amorphous silica. Anyway, if you zoom the viewer out (mouse wheel) then you should then see a monoclinic box of silica!