Pseudo-Jahn-Teller Centers and Local Structure of Doped Cuprates

Abstract

We consider a model where the most exciting features of the hole centers CuO 5- 4 in doped cuprates are in their unusually complicated ground state as a result of electronic quasi-degeneracy accompanied by the (pseudo-)Jahn-Teller effect. An additional hole, doped to the basic CuO 6- 4 cluster with the b 1g hole can occupy both the same hybrid Cu3d-02p orbital state resulting in a Zhang-Rice singlet 1 A 1g and the purely oxygen e u molecular orbital resulting in the singlet or triplet 1.3 E u term with close energies. We present a detailed analysis of the (pseudo-)Jahn-Teller effect and local structure distortions driven by the near-degeneracy within the ( 1 A 1g , 1,3 E u ) manifold.