Communication: Towards ab initio self-energy embedding theory in quantum chemistry

Area of Science:

• Quantum Chemistry
• Computational Physics

Background:

• Self-Energy Embedding Theory (SEET) was developed to address electron correlation in materials.
• SEET offers accuracy improvements by increasing perturbation order or active space size.
• Previous calibration on the 2D Hubbard lattice showed promising results.

Purpose of the Study:

• Extend SEET to quantum chemical ab initio Hamiltonians for molecular systems.
• Apply SEET to study physical and chemical properties of challenging molecules.

Main Methods:

• Employed self-consistent second-order Green's function method for non-local correlations.
• Utilized full configuration interaction for strong correlation within the active space.
• Applied SEET to proof-of-concept molecular examples.

Main Results:

• SEET demonstrated comparable quality to n-electron valence state second-order perturbation theory.
• The full active space in SEET can be divided into smaller subspaces.
• SEET successfully avoids intruder states and high-order reduced density matrices.

Conclusions:

• SEET is a promising method for describing properties of molecules with large active spaces.
• The extension of SEET to ab initio Hamiltonians broadens its applicability.
• SEET offers a robust and accurate approach to quantum chemical calculations.