Reexamination of the structures and energies of Li₂C₂ and Li₄C₄

Reexamination of the structures and energies of Li₂C₂ and Li₄C₄

  The structures and energies of Li₂C₂ and Li₄C₄ have been reexamined by DFT and MP2 methods using a variety of basis sets of 6-311+G(3df) and cc-pVXZ(X=T,Q,5). Two low-lying isomers are found as the local minima on the potential energy surfaces of Li₄C₄. the lowest energy structure is shown to be multiply bridged D₂<SUB>h</SUB> form. A newly found quadruply bridged C<SUB>i</SUB> form is found to be a local minimum, lying in energy above D₂h form by 22kj/mol in the energy. Also the energetics of high-lying isomers such as tetralithiotetrahedrane isomers were evaluated and discussed.   ⓒ 2005 Elsevier B. V. All rights reserved.