Debye

Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Molecules with symmetry point groups or containing inversion symmetry do not have a permanent dipole moment, while highly ionic molecular species have a very large dipole moment, e.g. gas-phase potassium bromide, KBr, with a dipole moment of 10.41 D. A proton and an electron 1 Å apart have a dipole moment of 4.8 D.

The debye is still used in atomic physics and chemistry because SI units have until recently been inconveniently large. The smallest SI unit of electric dipole moment is the quectocoulomb-metre, which corresponds closely to 0.3 D.