Periodic Boundary Conditions (PBC)

Tutorial 6 - Transform a Face-Centered Unit Cell of Diamond Crystal to a Primitive Unit Cell, PBC/3D

6-1  F follow steps 4-1 through 4-8 of PBC Tutorial 4.

6-2  In the "Cell" tab of the PBC dialog, push down the "Place" button and select "a (1,0,0)" instead of "0 (0,0,0)" to enable placement of the head of the "a" lattice vector at any atom selected in the view window using the mouse.  In the view window, click on atom 7.

6-3  In the "Cell" tab of the PBC dialog, push down the "Place" button and select "b (0,1,0)" instead of "a (1,0,0)" to enable placement of the head of the "b" lattice vector at any atom selected in the view window using the mouse.  In the view window, click on atom 3.

6-4  In the "Cell" tab of the PBC dialog, push down the "Place" button and select "c (0,0,1)" instead of "b (0,1,0)" to enable placement of the head of the "c" lattice vector at any atom selected in the view window using the mouse.  In the view window, click on atom 5.

6-5  In the "Cell" tab of the PBC dialog, select "Delete All Atoms Outside Cell" from the "Trim Contents" popup menu.

6-6  In the "Contents" tab of the PBC dialog, select "Rebond All" from the "Bonds" popup menu.

6-7  In the "View" tab of the PBC dialog, select "Dull" from the "Replicate Contents Format" combobox.

6-8  We now have a primitive unit cell for diamond crystal which gives the same crystal structure as that from the face-centered cubic unit cell we started with.

6-9  In the "View" tab of the PBC dialog, check the "Show All Boundary Atoms" checkbox.