Polarons in Quantum Materials

• Grant number: 25/08647-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Gustavo Martini Dalpian
• Grantee: Daniel de Martini Rivera Ferreira
• Supervisor: John P Perdew
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Tulane University, United States
• Associated to the scholarship: 23/03493-0 - Symmetry breaking in condensed matter: from wavefunctions to crystal structures, BP.DD

Abstract

Doping is a central strategy in tuning the electronic properties of quantum materials, often giving rise to emergent phenomena such as unconventional superconductivity or metal-insulator transitions, for example. However, understanding how the doped charge carriers interact with the lattice and the pre-existing electronic structure remains a significant challenge-particularly due to the possible formation of polarons, which can strongly renormalize the carrier dynamics. This project aims to study polaron formation in quantum materials using Density Functional Theory (DFT) as the main computational framework. We will model the ground state (GS) of representative materials by applying controlled symmetry breaking in spin, charge, orbital, and other sectors, enabling a natural description of strong correlation effects. To further improve the physical accuracy of orbital energies and electron localization, we will adopt corrective schemes such as DFT+$U$, not simply to mimic correlation but to try to impose the generalized Koopmans condition. In addition, we will perform systematic comparisons across different exchange-correlation functionals, especially those higher on Jacob's ladder, evaluating their performance on polaron formation in symmetry-broken regimes. This study aims not only to provide a deeper understanding of the nature and stability of polarons in correlated systems, but also to help clarify the complex interplay between various symmetry-breaking mechanisms in quantum materials, ultimately contributing to a more predictive modeling of doped systems. Furthermore, the project is also committed to the training and academic development of the student by promoting a one-year research visit to the internationally recognized group led by Professors John P. Perdew and Adrienn Ruzsinszky. During this period, the student will work in close collaboration with their team, deepening his understanding of quantum materials, symmetry breaking, and density functional approximations. (AU)