Interaction of Dipoles The van der Waals Bond

The van der Waals forces act between dipoles of molecules. These forces are referred to as dipole-dipole, dipole-induced and dispersion forces. 

In a dipole molecule a center of the positive charge -tq is separated from a center of a negative charge —q. The dipole moment p of the molecule is given by 

Interatomic BoniUngin Solids FundcanentaIs,Simulation,andApplications, First Edition. Valiin Levitin. 

In the solid, successive molecules have electric dipole moments which alternate in orientation so as to produce successive attractions. 

A net interaction between two dipole molecules can be expressed in polar coordinates Oi, O2, and 0 as 

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Interaction of Dipoles The van der Waals Bond 235 interaction. The averaging of the energy over all orientations leads to... 

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