Second-order electronic correlation effects in a one-dimensional metal

TL;DR

This paper investigates second-order electronic correlation effects in a one-dimensional metal using the PPP model, extending the Hubbard model to include long-range interactions, and compares results with coupled-cluster data for 3D systems.

Contribution

It applies second-order perturbation theory to the PPP model for 1D metals, highlighting the importance of long-range interactions and providing insights into the metallic state's nature.

Findings

Second-order correlation corrections to energy and bands calculated.

Qualitative similarity with 3D electron-gas coupled-cluster results.

Supports the hypothesis that the 1D metallic state differs from the ground state.

Abstract

The Pariser-Parr-Pople (PPP) model of a single-band one-dimensional (1D) metal is studied at the Hartree-Fock level, and by using the second-order perturbation theory of the electronic correlation. The PPP model provides an extension of the Hubbard model by properly accounting for the long-range character of the electron-electron repulsion. Both finite and infinite version of the 1D-metal model are considered within the PPP and Hubbard approximations. Calculated are the second-order electronic-correlation corrections to the total energy, and to the electronic-energy bands. Our results for the PPP model of 1D metal show qualitative similarity to the coupled-cluster results for the 3D electron-gas model. The picture of the 1D-metal model that emerges from the present study provides a support for the hypothesis that the normal metallic state of the 1D metal is different from the ground state.