Diagrams in Polaritonic Coupled Cluster Theory

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Spectroscopy

Background:

• Standard electronic coupled-cluster (CC) theory is a powerful tool for electronic structure calculations.
• Quantum electrodynamics (QED) describes interactions between light and matter, crucial for understanding phenomena like polaritons.
• Existing methods may not fully capture the complex interplay in QED-CC systems.

Purpose of the Study:

• To develop a generalized diagrammatic notation for deriving quantum-electrodynamic coupled cluster (QED-CC) equations.
• To enable the accurate description of polaritonic ground and excited states.
• To facilitate the calculation of molecular properties within QED-CC frameworks.

Main Methods:

• Generalization of standard electronic CC diagrammatic notation.
• Derivation of QED-CC and QED-Equation-of-Motion CC (QED-EOM-CC) equations.
• Presentation of diagrams for CC Lambda-equations and reduced density matrices.

Main Results:

• A novel diagrammatic notation for QED-CC theory is presented.
• The notation is used to derive QED-CC and QED-EOM-CC equations for specific truncation schemes (QED-CCSD-1-SD, QED-CCSD-12-SD).
• Diagrams essential for calculating molecular properties are provided.

Conclusions:

• The developed diagrammatic notation offers a systematic approach to QED-CC theory.
• This formalism is applicable to the study of polaritonic systems and molecular properties.
• The work provides a foundation for advanced computational studies in QED-influenced chemistry.