The molecular structure of C6: A theoretical investigation

摘要

The question of the lowest energy structure of the C6molecule has been addressed using high level of theoryabinitiomethods such as the coupled cluster and multiconfiguration perturbation theory approaches. The results show that the linear cumulenic chain and the monocyclic sixhyphen;membered ring structure withD3hsymmetry are very close in energy, indicating that both structures may be observed experimentally. The hexagonal sixhyphen;membered ring structure ofD6hsymmetry was confirmed as a saddle point geometry. These results are in partial contradiction with two earlierabinitiostudies that either find the distorted hexagon structure lsqb;Raghavachari, Whiteside, and Pople, J. Chem. Phys.85, 6623 (1986)rsqb; or the linear cumulenic chain lsqb;V. Parasuk and J. Almlouml;f, J. Chem. Phys.91, 1137 (1989)rsqb; to be the lowest energy structure.