A b i n i t i o Hartree–Fock crystal orbital studies. II. Energy bands of an infinite carbon chain

An ab initio restricted Hartree–Fock study of an infinite carbon chain is undertaken. In the equidistant model there appears a charge-density wave solution with lower total energy indicating that the alternating structure is energetically more favorable. Indeed, the alternating model is found to be energetically much more stable. The most stable geometry is predicted with alternating bonds with an average of 1.275±0.005 Å and an alternation of 0.26±0.02 Å. The nature of the CDW is remarkable: two out-of-phase waves with the same amplitude appear in the perpendicular π-electron systems.