A method named for the fragment type of these structures uses energy decomposition analysis and Møller–Plesset perturbation theory for efficient calculation. (-5[1])Repulsion in these structures is described by the Klopman–Salem equation. To approximate wave functions of these structures, the Hartree–Fock method uses the overlap integral between (15[1])Gaussian basis functions. Depending on their behavior under inversion, these structures are categorized as (*) “gerade” or “ungerade.” The “frontier” (10[1])theory of these structures (10[1])examines their “highest occupied” and “lowest unoccupied” examples. (10[1]-5[1])Electrons (10[1])generally occupy the “bonding” variety of these structures before their “antibonding” variety. Sigma and pi-star are examples of, for 10 points, what structures classically formed from the linear combination of atomic orbitals? ■END■ (10[1])