Geometries and electronic structures of negatively charged carbon clusters

Self-consistent field molecular orbital calculations have been performed on neutral and negatively charged clusters of carbon atoms using an extended basis set designed to obtain correct electron affinity. Correlation effects have been included perturbatively up to second order. The optimized geometries of theC _n ^? (n ≤ 7) anions are all linear chains as observed in experiments. The calculated electron affinities are comparable with experimental data. Studies of the stabilities of doubly charged anions show that clusters uptoC ₇ ^?? are unstable.