Quantum Embedding Methods for Correlated Excited States of Point Defects

Explore quantum embedding methods for correlated excited states of point defects in a 52-minute lecture presented by Lukas Muechler from Penn State University. Delve into the challenges of describing excited electronic states of point defects and impurities, crucial for understanding materials properties and potential applications in quantum technologies. Learn about the implementation of an embedding approach based on Wannierization of defect orbitals and the constrained random-phase approximation. Examine case studies on three technologically relevant systems: a carbon dimer in hexagonal BN, the negatively charged nitrogen-vacancy center in diamond, and an Fe impurity in wurtzite AlN. Gain insights into the effects of DFT functionals, double-counting corrections, and challenges associated with determining energies and orderings of complex spin multiplets.

Introduction
Background
What are we interested in
Defects in condensed matter
Applications of point defects
Energy scale of point defects
Field of Quantum Materials
Motivation
Embedding theories
How does the method work
Defining the correlated subspace
Linear functions
Assumptions challenges
Quantum chemical approach
Small active space
Heart rate fog
Results
Dependence of DFT
Double counting
Double counting with HSE
Twosided hybrid model
Conclusion