A face-centred cubic cell has eight corners and six face centres. A face belongs to two cells, so the count is 8 × ⅛ + 6 × ½ = 4. Contact is along a face diagonal: 4r = √2 a.
A face-centred cubic cell has eight corners and six face centres. A face belongs to two cells, so the count is 8 × ⅛ + 6 × ½ = 4. Contact is along a face diagonal: 4r = √2 a.