Good and Girifalco Approach

Good and Girifalco [10, 11] proposed a more empirical approach to the problem of calculating the surface and interfacial tension. The interaction constant for two different particles was assumed to be equal to the geometric mean of the interaction constants for the individual particles. This is referred to as the Berthelot principle. 

For two atoms i and j with London constants and Pj, the interaction constant Pij is given by 

Similarly the Hamaker constant Ay is given by the geometric mean of the individual Hamaker constants. 

By analogy Good and Girifalco [10] represented the work of adhesion between two different liquids W u as the geometric mean of their respective works of cohesion, 

The interfacial tension y 2 is then related to the surface tension of the individual liquids and yj by 

---