Analysis of static and dynamic electron and spin properties within the interaction space of the one-dimensional Hubbard chain; a path-integral quantum Monte Carlo approach

Abstract

Feynman path-integral quantum Monte Carlo (QMC) simulations have been performed to investigate electronic structure properties of the one-dimensional (1D) Hubbard chain. On the basis of the calculated on-site densities 〈 n i 〉 the following electronic configurations can be discriminated: (i) symmetry nonbroken 〈 n i 〉 distributions, (ii) on-site charge density waves (CDWs), (iii) clusters, (iv) statistical 〈 n i 〉 distributions resulting from chaotic QMC trajectories. The stability region for the different configurations is discussed as a function of the average electron density 〈 n〉 and the parameters of the extended Hubbard Hamiltonian, the two-electron elements U, V and the kinetic hopping t. It is suggested that the formation of cluster structures is a position-space concomitant of superconducting configurations in the 1D chain. The role of attractive on-site elements U and attractive intersite couplings V are analyzed in detail. The conditions stabilizing on-site CDWs are compared with the conditions favouring cluster formation. The static and dynamic electronic properties are discussed in terms of the on-site densities 〈 n i 〉 of the monoatomic 1D chain, electronic charge and spin fluctuations 〈Δ n 2)〉, 〈(Δ s 2)〉 and the probability of double occupancy P(2). Prerequisites leading to simultaneous and nonsimultaneous occurrence of charge and spin degrees of freedom are formulated. The possible violation of particle—hole (ph) symmetry in the presence of attractive on-site elements U is discussed. Consequences emerging from ph violation in charge transfer salts are also considered. It is suggested that low-temperature superconductivity in these materials is supported by attractive intersite interactions.