García Bach, Ma. de los ÁngelesBlaise, P.Malrieu, J. P.2009-10-202009-10-2019920163-1829https://hdl.handle.net/2445/9734Extracting a bond-length-dependent Heisenberg-like Hamiltonian from the potential-energy surfaces of the two lowest states of ethylene, it is possible to study the geometry of polyacetylene by minimization of the cohesive energy, using both variational-cluster and Rayleigh-Schrödinger perturbative expansions. The dimerization amplitude is satisfactorily reproduced. Optimizing the variational-cluster-expansion total energy with the equal-bond-length constraint, the barrier to reversal of alternation is obtained. The alternating-to-regular phase transition is treated from the Néel-state starting function and appears to be of second order.7 p.application/pdfeng(c) The American Physical Society, 1992PolímersElastòmersQuímica físicaPolymersElastomersPhysical chemistryinfo:eu-repo/semantics/article10987info:eu-repo/semantics/openAccess