Quantum Embedding Theory for Strongly Correlated States in Materials

Area of Science:

• Quantum embedding theories
• Materials science
• Condensed matter physics

Background:

• Strongly correlated electronic states in large molecular or condensed systems are challenging to study.
• Spin defects in semiconductors and insulators are key examples requiring advanced theoretical investigation.

Purpose of the Study:

• To present a detailed derivation of a novel quantum embedding theory.
• To generalize the theory for active spaces not limited to Kohn-Sham Hamiltonian eigenstates.
• To apply the theory to investigate spin defects in semiconductors.

Main Methods:

• Development of a quantum embedding theory based on effective Hamiltonians.
• Incorporation of environmental effects via screened Coulomb interactions using density functional theory.
• Circumvention of virtual electronic orbital evaluation, avoiding the random phase approximation.

Main Results:

• A generalized quantum embedding theory is derived and detailed.
• The theory successfully accounts for environmental effects on active spaces.
• Application to spin defects in semiconductors demonstrates the theory's efficacy.

Conclusions:

• The presented quantum embedding theory provides an efficient and versatile tool for studying strongly correlated electronic systems.
• The method avoids computationally expensive approximations and evaluations, making it suitable for large-scale systems.
• This work advances the theoretical understanding and computational investigation of spin defects and similar phenomena.