Editing Angular momentum coupling (section)

== Nuclear coupling ==

In atomic nuclei, the spin–orbit interaction is much stronger than for atomic electrons, and is incorporated directly into the nuclear shell model. In addition, unlike atomic–electron term symbols, the lowest energy state is not {{mvar|L&nbsp;&minus;&nbsp;S}}, but rather, {{mvar|ℓ&nbsp;+&nbsp;s}}. All nuclear levels whose {{mvar|ℓ}} value (orbital angular momentum) is greater than zero are thus split in the shell model to create states designated by {{mvar|ℓ&nbsp;+&nbsp;s}} and {{mvar|ℓ&nbsp;&minus;&nbsp;s}}. Due to the nature of the [[Nuclear shell model|shell model]], which assumes an average potential rather than a central Coulombic potential, the nucleons that go into the {{mvar|ℓ&nbsp;+&nbsp;s}} and {{mvar|ℓ&nbsp;&minus;&nbsp;s}} nuclear states are considered [[Degenerate energy levels|degenerate]] within each orbital (e.g. The 2{{math|p}}{{sfrac|3|2}} contains four nucleons, all of the same energy. Higher in energy is the 2{{math|p}}{{sfrac|1|2}} which contains two equal-energy nucleons).