# Crystal

crystal allows to display crystal projection on a plane and draw dichromatic patterns.

## Interface¶

The interface is composed of a top bar menu, a plotting area to display the projection and a setting panel.

## Procedure¶

• Enter the Crystal Parameters, either from the input fields or from the structure menu

• Fill the Plane field and the Size of the crystal box (integer units of the lattice parameters).

• Enter the layers indices (Layers numb.) parallel to the projected plane according to the scheme $n_0,n_1$, $n$ being the layer number.

• Press the Calculate button. You will be prompted to select the appropriate crystal structure. Text files such as cfc.txt describe the position of atoms in the unit cell. The format is:

atom1 x1 y1 z1

...

atomn xn yn zn

v1x v1y v1z

...

vkx vky vkz


with atomn is nth atom in the cell at coordinate xn, yn, zn and vkx,vky,vkz is the kth translation vector defining all the positions of atoms in the cell.

• Press the Draw button.

• Tick Atom type button to see the different atoms (label with different numbers)

• Tick Atom position button to see the coordinates

Projection of 3 layers of the $(1,1,1)$ plane in an Al crystal

### Layout¶

• Change the Marker size and shape using the Square/circle button

• Zoom in, move and save the figure using the tool bar

## Dichromatic pattern¶

A so-called dichromatic pattern is formed when two misoriented crystals are interpenetrated. The pattern is drawn according the usual convention: black and white crystals correspond to two different grains and different symbols to different layers (note that you can plot up to 7 different layers with different symbols).

• To draw it tick the enable box

• Enter a rotation angle between the two crystal along the plane normal.

• Recalculate (press Calculate) and then Draw

• Tick the coincidence box to highlight coincident site positions. The precision by which is defined coincidence can be tuned in the precision field. It is expressed in % of the largest lattice parameter.

• Tick the layers button to show the layer number on the dichromatic pattern. From layers 0 to 5, markers are circles, squares, triangles, stars and hexagons, respectively. After they are all circles.

Example of a dichromatic pattern in a $(1,1,1)$ plane with a misorientation angle of 38.21°, in Al.