This model tends to provide a good approximation when there is no departure from the LandÃ© interval rule. It has been shown to fail in the 5f states 
This model tends to provide a good approximation when there is no departure from the LandÃ© interval rule. It has been shown to fail in the 5f states of plutonium, which demonstrates the general rule that it is less useful for elements with atomic number greater than thirty. This happens because this scheme assumes that the electrostatic interaction in atomic systems between two inequivalent electrons will be stronger than spin-orbit interaction, which is untrue in heavier atoms. In those cases, this model can be replaced with the J-J scheme ►of coupling. FTP, name this other form of coupling, also known as L-S coupling, named for a Princeton astronomer and a Harvard physicist.
This model tends to provide a good approximation when there is no departure from the LandÃ© interval rule.
Russell-Saunders coupling (or accept L-S coupling before mentioned) 