# ‘Interaction annealing’ to determine effective quantized valence and orbital structure: an illustration with ferro-orbital order in WTe2

## TL;DR

This paper introduces a new method called 'interaction annealing' to study the electronic structure of complex materials like WTe2, revealing insights into their low-energy behaviors.

## Contribution

The novel 'interaction annealing' approach is introduced to suppress charge fluctuations and determine effective quantized electronic structures in correlated materials.

## Key findings

- Interaction annealing successfully reveals an emergent local electronic structure in WTe2.
- The method provides a new explanation for experimental observations in highly fluctuating 5d semi-metals.
- It is effective in studying competing local electronic structures in functional materials.

## Abstract

Correlated materials are known to display qualitatively distinct emergent behaviors at low energy. Conveniently, upon absorbing rapid quantum fluctuations, these rich low-energy behaviors can always be effectively described by dressed particles with fully quantized charge, spin, and orbital structure. Such a powerful and simple description is, however, difficult to access through bare particles used in most many-body computations, especially when fluctuations are strong such as in 4d and 5d compounds. To decipher the dominant quantized structure, we propose an easy-to-implement ‘interaction annealing’ approach that utilizes suppressed charge fluctuation through enhancing ionic charging energy. We establish its theoretical foundation using an exactly treated two-site Hubbard model as a generic example. We then demonstrate its applications with more affordable density functional calculations to a representative 3d Mott insulator La2CuO4 and a highly fluctuating 5d semi-metal WTe2. In the latter, it reveals an emergent local electronic structure that makes possible an unprecedented explanation of several experimental observations. Finally, we demonstrate the effectiveness of this approach in studying competing local electronic structures in functional materials.