https://doi.org/10.1351/goldbook.CT06770
The average static electric field experienced by an ion, molecule or atom in a crystal generated by all the other surrounding atoms, molecules, or ions. The concept introduced by @B00624@ and developed by Bethe has been extended to refer to the field generated by the @L03518@ (anions or neutral species) surrounding a transition metal ion in a @C01329@ compound. With the understatement that some covalency may exist in the metal-ligand bond, it is often referred to as @LT06764@.