Multiband Hubbard Models and the Transition Metals

TL;DR

This paper explores multiband Hubbard models for transition metals, emphasizing the importance of degeneracy and exchange interactions, and discusses how various computational methods relate to experimental properties, highlighting the unique case of iron.

Contribution

It demonstrates the significance of proper degeneracy and exchange interactions in multiband Hubbard models and connects different computational approaches to experimental observations.

Findings

Correlation computations elucidate the role of degeneracy and exchange interactions.

Most elemental properties can be explained with a unified parameter set.

The Tc of Fe requires consideration of longer-range interactions, as shown by ab-initio results.

Abstract

Correlation computations on multiband Hubbard Hamiltonians are presented. It is shown why the proper degeneracy is of vital importance and that the atomic exchange interaction plays a particular role. The different methods are connected, and their results are discussed. Many experimental properties for the elemental solids can be explained by single closely related sets of parameters each. There is an exception, Tc of Fe. Here, a novel feature of longer-range interactions enters, as demonstrated on ab-initio results of the Local Ansatz for Fe. Connections are made to LSDA-calculations; and their seeming successes and deficiencies are explained.