Surface energy of multi-component systems

For a sufficiently large system, such as a homogenous fluid or a heavy atomic nucleus, the total energy of the system may be approximated as a sum of a volume energy (proportional to the volume V of the system) and a surface-layer energy. The surface-layer energy is approximately proportional to the area S of the surface bounding the system. The surface-energy coefficient γ (i.e., the surface energy per unit area of a flat surface) must be consistently defined in formulating macroscopic descriptions of nuclei