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We present a density functional theory (DFT) calculation in the generalizedgradient approximation to study the possibility for the existence ofJahn-Teller (JT) or pseudo Jahn-Teller (PJT) type local distortions in theLa-Ba-Cu-O superconducting system. We performed the calculation andcorrespondingly group theory classification of the electronic ground state ofthe CuO${_{6}}^{-10}$ elongated octahedra cluster, immersed in a backgroundsimulating the superconductor. Part of the motivation to do this study is thatthe origin of the apical deformation of the CuO${_{6}}^{-10}$ cluster is notdue to a pure JT effect, having therefore a non {\it a priori} condition toremove the degeneracy of the electronic ground state of the parent regularoctahedron. We present a comparative analysis of the symmetry classifiedelectron spectrum with previously reported results using unrestrictedHartree-Fock calculations (UHF). Both the DFT and UHF calculations produced anon degenerate electronic ground state, not having therefore the necessarycondition for a pure JT effect. However, the appearance of a degenerate E$_{g}$state near to the highest occupied molecular orbital in the DFT calculation,suggests the possibility for a PJT effect responsible for a local distortion ofthe oxidized CuO$_{6}^{-9}$ cluster.Comment: 12 pages, 3 figures, submitted to International Journal of Modern  Physics B (IJMPB

international journal of modern physics b/international journal of modern physics b

DENSITY FUNCTIONAL ELECTRONIC SPECTRUM OF THE CuO6-10 CLUSTER AND POSSIBLE LOCAL JAHN–TELLER DISTORTIONS IN THE La–Ba–Cu–O SUPERCONDUCTOR