Charge localization and stripes in a two-dimensional three-band Peierls-Hubbard model

Abstract

Using a two-dimensional three-band Peierls-Hubbard model appropriate to layered transition-metal oxides, and in an inhomogeneous Hartree-Fock approximation, we show that several kinds of charge-localized mesoscopic patterns (stripes) may exist: vertical site stripes, vertical zig-zag stripes, diagonal site stripes, and oxygen-centered stripes. A random-phase-approximation analysis reveals new phonon modes and intense low-energy spin excitations in these stripes. A softened phonon mode with momentum ({pi},0) in the oxygen-centered stripe may explain the anomalous phonons observed by neutron-scattering experiments in several cuprate superconductors. {copyright} {ital 1998} {ital The American Physical Society}