Flake Growth — Guide
14. June 2020The 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 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.

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!