Numerical computation of surface areas of molecules

For a cubical tesselation of a finite region of space which contains an irregularly shaped surface, a fairly accurate estimate of the surface area is 2/3N a ², whereN is the total number of cubes cut by the surface and a is the length of the edges of the cubes. An estimate of slightly improved accuracy can be obtained by using different increments to the surface area, depending on the number of edges of the corresponding cube cut by the surface and the number of vertices on either side of the surface.