Bonding and Antibonding Molecular Orbitals
The lowest-energy bonding and antibonding molecular orbitals (MO) for a homonuclear diatomic molecule are shown, as the internuclear distance is varied. These MOs are designated 1 (or 1s) and 1 (or 1s), respectively. The red contours designate negative values of the wavefunction. In the separated atom limit (large ), the MOs approach a pair of noninteracting 1s atomic orbitals. In the united atom limit (), the 1 and 1 collapse to 1s and 2atomic orbitals, respectively. At the equilibrium internuclear distance, when the red dot is at the minimum of the energy curve, the bonding orbital is optimally effective.
The contour curves take a few seconds to smooth out as you change . Only qualitatively representative results are intended.
Snapshot 1: equilibrium internuclear distance
Snapshot 2: separated atoms
Snapshot 3: united atoms