◾ Unit Cell Calculations
Maureen M. Julian · 2014
If there is an atom at fractional coordinates (0.50, 0.67), then there is also an identical atom at the following fractional coordinates, as can be seen in Figure 2.2: (0.50, 0.67) atom A in cell A (1.50, 0.67) atom A in cell B (0.50, 1.67) atom A in cell C (2.50, 0.67) atom A in cell D (0.50 − 1, 0.67) = (−0.50, 0.67) atom A in cell E EXAMPLE 2.1 (continued) Solution First, draw the basis vectors to form the unit cell in Figure 2.1. Multiply the fractional coordinates, x and y, by a and b as follows: x a = 0.50 a = 0.50 × 10 Å = 5.0 Å y b = 0.67 b = 0.67 × 10 Å = 6.7 Å.