上浒充通大粤 SHANGHAI JIAO TONG UNIVERSITY Approximate Calculation of Solid Surface Energy (2) If we cleave a face-centered cubic crystal along a(111)plane,three bonds per atom will be broken.Two surfaces formed,the work required to form the surfaces will be 38/2 per surface atom. 3 W= △Hs V6/4a (for Z=12) △Hs E 2 ANA 0.5ZN4 △Hs Y= v2/2ao 4N, aov 2 N/A is the number of atoms per unit (Face diagonal) area.For fec structure: Figure 4.2 Atomic packing on the (111)face of a face-centered N 4 cubic crystal. A 2,* A/N= a=3a2 4 4Approximate Calculation of Solid Surface Energy （2）