Hi, how can I determine how many atoms there are in the unit cell. I understand what the lattice vectors should be but to get the unit cell from that and the amount of atoms is confusing to me. Thank you!
We can determine the number of atoms in a unit cell by simply counting the fractions of atoms inside the “drawn” cell. For example:
Here we have 1/4’th of an atom for each corner, and 1 entire atom in the middle. Thus the number of atoms in the unit cell is 1/4 * 4 + 1 = 2.
The following section from the lecture notes explains exactly this for the fcc lattice:
Hope this helps!