Flake Growth — Guide

The program starts with a single gold atom.

Intentionally add atoms to the fcc lattice using the keys: A (west), D (east), Y (southwest), C (southeast), Q (northwest), E (northeast), W (layer up) and X (layer down).

Highlight the last atom with S.

Reset the crystal via :.

Add a layer via L.

Of course, via W D D C Y Y A some atoms can be added to the layer, too.

Show all surface vacancies by pressing F.

Show the instrument overlay via R:

Top left: Number of overall atoms, surface atoms and surface vacancies sorted by coordination number.
Top right: Layer arrangement (gold, silver, bronze => layers A, B, C; red => stacking fault; substrate).
Bottom left: Number of added atoms and the time it took to add them.
Bottom right: Height, width and depth of the flake as well as its aspect ratio (typical length over high) and shape ratio (0.5 => hexagon, +/-1 => triangle).

Hide all surface vacancies that are in contact with only one gold atom (coordination number 1) via F1.

Hide surface vacancies with coordination number 2 via F2.

Hide surface vacancies with coordination number 3 via F3. Now only surface vacancies with coordination numbers 4-7 are left (8 & 9 are not occupied).

Randomly add one atom by pressing 1.

Randomly add another atom by pressing 1,

and yet another atom by pressing 1,

and another,

and another,

and another,

and another.

Now, randomly add ten atoms by pressing 2,

hundred atoms by pressing 3,

thousand atoms by pressing 4,

and 10,000 atoms by pressing 5,

Zooming out is possible via the mouse wheel.

All vacancies can be shown again by pressing F twice.

A simplified (and much faster) representation can be activated by switching off the gold atoms via G and enabling the hexagon approximation by pressing H.

Now, after randomly adding one million atoms via 7 one can still quickly navigate the scene.

Note, the rendering of individual atoms is very slow for large quantities and therefore not automatically done when growing with 6, 7, 8 or 9. Though, pressing G twice (hide/show the gold atoms) will update the scene.

You can add/remove the substrate by pressing arrow down .

The stacking faults can be removed by pressing arrow up . When resetting the crystal via : and regrowing it à la 3 3 3 3 3 3 4 one obtains a completely different geometric shape.

Stacking faults can be added to the current upper or lowermost layer via PgUp or PgDn, respectively. The depicted shape can more or less (it is still random) achieved via : PgUp 4 4 4.

Obtaining a proper flake with two stacking faults can be achieved by: resetting the atoms and stacking faults : , growing a seed 3 3, adding the stacking faults PgUp PgDn, resetting the atoms : and grow a large number 5.

To visualize the different layers V is your friend.

And by pressing P you can cycle through the different probability lists and watch how they influence the growth.

If you want to obtain a high aspect ratio you should not use p1.

Finally, Space gives you an overview over all available actions.

That’s basically it. Have fun!