Pseudo-Jahn-Teller centers and local structure of doped cuprates

We consider a model where the most exciting features of the hole centers Cu O45- in doped cuprates are in their unusually complicated ground state as a result of electronic quasi-degeneracy accompanied by the (pseudo-)Jahn-Tel ler effect. An additional hole, doped to the basic CuO46- cluster with the b(1g) hole can occupy both the same hybrid Cu3d-O2p orbital state resulting in a Zhang-Rice singlet (1)A(1g) and the purely oxygen e(u) molecular orbi tal resulting in the singlet or triplet term with close energies. We presen t a detailed analysis of the (pseudo-)Jahn-Teller effect and local structur e distortions driven by the near-degeneracy within the ((1)A(1g), E-1,3(u)) manifold.