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Applet Tutorial

Functions:

1. black background option:  toggles between black and white color as the background color

2. perspective option: gives 3D perspective to the unitcell.

3. 14 Bravais Lattices: Select any lattice from the list.  Default is the Simple Cubic (sc) lattice.

4. the Grid Slider:  increase or decrease the number of unitcells in the view. When grid is equal to 1, it will show only one, 1x1x1, unit cell.  When grid equals 5, it displays 5x5x5 (125)  unitcells.  More unitcells make mouse rotation of structure slower.

5.  Lattice Parameter Set button: Sets lattice parameters for the crystal.

The Set Button:  the new parameters in the textfields take effect.

The unitcell parameters of the 7 crystal systems follow these rules:

• Cubic: a = b = c, alpha = beta = gamma = 90
• Hexagonal: a = b, alpha = beta = 90, gamma = 120
• Monoclinic: a != b != c, c<a, alpha = gamma = 90, beta > 90
• Orthorhombic: a != b != c, c < a < b, alpha = beta = gamma = 90
• Tetragonal: a = b != c, alpha = beta == gamma = 90
• Triclinic: a != b != c, c < a < b, alpha != beta != gamma != 90
• Trigonal: a = b = c, alpha = beta = gamma != 60 != 90 != 109.28

6. Basis atoms: A real crystal structure consists of the underlying Bravais lattice and a group of atoms attached to each lattice point, called Basis.  By typing in the relative coordinate values (in the units of lattice parameters, a,b and c), you can add a new atom to the Basis.

Different atoms with Color Value  can be used by clicking on the Color box.  You can choose different colors for different atoms in the Basis and set an appropriate Atom size using the drop-down box.

The Basis Atoms list has the atoms you just added.  You can also delete the selected atom from the list by clicking on the rmv button.

On the bottom, there is the Basis library manager button.  You can save the Basis (with one or more atoms in it) you just designed for a later use.

7. Lattice Plane and Direction: Left-click on the Miller index of lattice plane to increase the index value.  Right-click decreases it.  Click the check box in front of the "-" sign on the top of the index number will change the sign.

Show checkboxes: to display or hide the (hkl) lattice Plane, the [hkl] Direction, and the lattice Points in the view.

8. Crystal Library: We have constructed many crystal examples in the Lib ready for view. User can directly select any of them.

9. For Rotation of the structure: Mouse drag with left button pressed on the crystal view can rotate the view.

10. Enlarge and shrink. Mouse drag on the structure with the right mouse button pressed  to enlarge or shrink the size of the crystal view.