A Review of Basic Intermolecular Forces

According to the theories introduced in Chapter 4, the force of attraction between two molecules as a function of the distance of separation is given by 

Employing the convention that attractive energy is negative, at infinite separation the energy of the system will be zero, so that the free energy of attraction at distance r will be 

FIGURE 10.5. A typicaP interaction energy curve for two interacting units (curve 3) is the sum of the attractive potential (curve 1) and the repulsive contribution (curve 2). 

The total free energy will be the sum of the attractive and repulsive terms 

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