Polarizability
Polarizability is the ability to form instantaneous dipoles. It is a property of matter. Polarizabilities determine the dynamical response of a bound system to external fields, and provide insight into a molecule's internal structure.
Electric polarizability
Definition
Electric polarizability is the relative tendency of a charge distribution, like the electron cloud of an atom or molecule, to be distorted from its normal shape by an external electric field, which is applied typically by inserting the molecule in a charged parallel-plate capacitor, but may also be caused by the presence of a nearby ion or dipole.
The polarizability is defined as the ratio of the induced dipole moment of an atom to the electric field that produces this dipole moment.
Polarizability has the SI units of C·m2·V−1 = A2·s4·kg−1 while its cgs unit is cm3. Usually it is expressed in cgs units as a so-called polarizability volume, instead of cm3 it is sometimes expressed in Å3 = 10−24 cm3. One can convert from SI units to cgs units as follows: