Multi-pole forces

Dipole forces or multi-pole forces, if the lattice components have dipoles or multipoles. Dipoles can be either intrinsic or induced. Depending on the orientation, the dipole-dipole interaction energy for linear-orientation (Figure 2.34a) is... 

In any case, once these multipoles are known, the interaction energies can be computed from standard formulas of electrostatics. Multi pole-induced multipolar interactions are known as Debye (or Falkenhagen) forces and like Keesom forces are important for bodies possessing permanent moments when interacting with polarizable bodies. 

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