The combined exact diagonalization - ab initio approach and its application to correlated electronic states and Mott-Hubbard localization in nanoscopic systems

TL;DR

This paper introduces the EDABI method combining exact diagonalization and ab initio calculations to study correlated electronic states in nanoscopic systems, revealing unique localization, magnetic, and transport phenomena related to Mott-Hubbard physics.

Contribution

The paper presents the EDABI approach applied to nanostructures, highlighting new insights into electron localization, magnetic splitting, and transport properties at the nanoscale.

Findings

Electron distribution evolves from Fermi-Dirac to Luttinger-liquid with increasing interatomic distance.

Hubbard subbands in nanoclusters correspond to HOMO-LUMO splitting.

Nanochains show magnetic splitting without symmetry breaking.

Abstract

We overview the EDABI method developed recently and combining the exact diagonalization and ab initio aspects of electron states in correlated systems and apply it to nanoscopic systems. In particular, we discuss the localization-delocalization transition for the electrons that corresponds to the Mott-Hubbard transition in bulk systems. We show, that, the statistical distribution function for electrons in a nanochain evolves from the Fermi-Dirac-like to the Luttinger-liquid-like with the increasing interatomic distance. The concept of Hubbard subbands is introduced to nanoclusters, and corresponds to the HOMO-LUMO splitting in the molecular and organic solid states. Also, the nanochains exhibit magnetic splitting (Slater-like), even without the symmetry breaking, since the spin-spin correlations extend over the whole system. Thus, the correlated nanoscopic systems exhibit unique and universal features, which differ from those of molecular and infinite systems. These features define unique properties reflecting "the Mott physics" on the nanoscale. We also employ the EDABI method to the transport properties in nanoscopic systems. For example, we show that the particle-hole symmetry is broken when the tunneling conduction through H2 molecule is calculated.