where α j represents either a scalar polarizability or a polarizability tensor, and in general E j = E j,ext + E j,perm + E j,ind , where the three contributions are the external field (if present), the field due to the permanent partial atomic charges on other atoms, and the field due to induced dipoles on other atoms. Because the value of each atom's induced dipole depends on the induced dipoles present on other atoms, induced dipoles are usually solved with a self-consistent field (SCF) method, also termed a mutual polarization method. This accounts fully for the contribution of the induced electric field (E j,ind ) from the induced dipoles on other atoms. The well-developed AMOEBA force field 25 uses this approach, along with a more detailed multipole representation of the permanent charge distribution.