Page 26 - Microsoft PowerPoint - lecture1.ppt

2.1 Basics of Structures

Number of atoms per unit cell (Z)

• Rectangular cells:

• atom completely inside unit cell: count = 1.0

• atom on a face of the unit cell: count = 0.5

• atom on an edge of the unit cell: count = 0.25

• atom on a corner of the unit cell: count = 0.125

Example 1: Sphalerite Example 2: Wurzite

number of atoms 2

number of atoms 1

• Wyckoff-notation: number of particular atom per unit cell