Comparison of Keesom, Debye and London interactions in polar molecules

3 Comparison of Keesom, Debye and London interactions in polar molecules 

As we have seen, London dispersion interactions, Keesom dipole-dipole orientation interactions and Debye dipole-induced dipole interactions are collectively termed van der Waals interactions their attractive potentials vary with the inverse sixth power of the intermol-ecular distance which is a common property. To show the relative magnitudes of dispersion, polar and induction forces in polar molecules, similarly to Equation (78) for London Dispersion forces, we may say for Keesom dipole-orientation interactions for two dissimilar molecules using Equation (37) that 

the Keesom dipolar orientation interaction coefficient, CP, can be written as 

We may say for Debye dipole-induced dipole interactions for two dissimilar molecules using Equation (60) so that 

the total van der Waals force is the sum of these three contributions 

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