In LCAO notation, what does the symbol 'e' represent?

In LCAO (Linear Combination of Atomic Orbitals) notation, the symbol 'e' is used to denote doubly degenerate orbitals. This means that there are two orbitals that have the same energy level and are symmetry-related. In many molecular symmetry contexts, particularly in point groups, degenerate orbitals arise in the molecular orbital theory due to the presence of symmetrical arrangements of atoms, which leads to the formation of orbitals that share the same energy.

In contrast, nondegenerate orbitals would be represented differently, as they do not have the same energy. Triply degenerate orbitals refer to a scenario with three orbitals of the same energy level, while higher energy orbitals would not be specifically denoted by 'e' in this notation. Understanding these distinctions is crucial for interpreting molecular symmetry and the properties of molecular orbitals in inorganic chemistry.