Structural changes in quasi- 1D many-electron systems: from linear to zig-zag and beyond

TL;DR

This study uses density functional theory to explore various charge and spin configurations in quasi-1D many-electron systems at low density, revealing structural transitions from linear to complex twisted chains.

Contribution

It provides a detailed computational analysis of structural and magnetic phase transitions in quasi-1D electron systems, including new insights into their stability and spin interactions.

Findings

Identification of diverse charge and spin configurations including zig-zag and helical structures.

Observation of a transition from antiferromagnetic to ferromagnetic spin coupling with decreasing density.

Analysis of the stability of linear chains through potential and excitation dispersion calculations.

Abstract

Many-electron systems confined to a quasi-1D geometry by a cylindrical distribution of positive charge have been investigated by density functional computations in the unrestricted local spin density approximation. Our investigations have been focused on the low density regime, in which electrons are localised. The results reveal a wide variety of different charge and spin configurations, including linear and zig-zag chains, single and double-strand helices, and twisted chains of dimers. The spin-spin coupling turns from weakly anti-ferromagnetic at relatively high density, to weakly ferromagnetic at the lowest densities considered in our computations. The stability of linear chains of localised charge has been investigated by analysing the radial dependence of the self-consistent potential and by computing the dispersion relation of low-energy harmonic excitations.