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The geometric and electronic structures and the total and binding (chemisorption) energies of linear Cn (n=6−10) and HCnH (n=2−10) molecules have been predicted via RHF ab initio calculations. For Cn clusters the bonding structures are predicted to be cumulene type, with n-even clusters having triplet ground states and n-odd species having singlet ground states. For HCnH molecules, the n-even species are predicted to have singlet ground states with polyyne-type bonding while the n-odd molecules are predicted to have triplet ground states with intermediate cumulene—polyyne-type bonding.

Restricted Hartree-Fock calculations have been carried out on linear LiCnLi (n=2–8) molecules. Ground state electronic structures, total energies, binding energies, and optimized geometries are reported. The possibility of basis set superposition error is examined. Extensive bond pattern change is found by comparison with linear Cn molecules.

Total energies, bond lengths, charge distributions, electronic configurations, and cohesive energies are calculated for linear Cn clusters, n = 2–6. The calculations are done at the single determinant Hartree-Fock level using both double-zeta and double-zeta plus polarization basis sets.

Configuration interaction of low‐lying electronic states is used to investigate the molecular correlation energy as a function of bond angle. Qualitative aspects of the problem are discussed using the molecular‐orbital diagrams of Walsh and Mulliken. Results of configuration‐interaction calculations of BeH2 and NO2+ are reported. The possibility of double minima in the potential surfaces for AB2 molecules is considered.

Describes a convenient procedure, the Odd-Even Rule, for predicting the allowedness or forbiddenness of ground-state, pericyclic reactions.