Which of the following has the lowest energy in LCAO notation?

In the context of molecular orbital theory and the Linear Combination of Atomic Orbitals (LCAO) method, the energy levels of molecular orbitals can be understood based on their characteristics. Bonding orbitals generally have lower energy than non-bonding or anti-bonding orbitals because they are formed by constructive interference between atomic orbitals, resulting in increased electron density between the nuclei.

The designation of orbitals into categories such as nondegenerate (a), doubly degenerate (e), and triply degenerate (t) relates to their symmetry properties and spatial distribution. In this context, the nondegenerate (a) orbital typically arises from the combination of atomic orbitals that results in a single energy level, distinct from the degenerate orbitals that share the same energy level due to their symmetry.

Bonding orbitals are formed from the lowest-energy combinations of atomic orbitals. When considering LCAO combinations, the most stable (lowest energy) configuration results from those combinations that maximize overlap, which is characteristic of bonding interactions.

Therefore, among the choices, the nondegenerate (a) orbital is considered to have the lowest energy because it represents a linear combination that results in greater electron overlap and