Reduced density matrix embedding. General formalism and inter-domain correlation functional.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Electronic Structure Theory

Background:

• Accurate calculation of molecular properties is crucial in chemistry.
• Existing embedding methods often struggle with strong correlation effects and exact kinetic energy treatment.
• The one-electron reduced density matrix (1-RDM) provides a computationally efficient alternative to wavefunctions.

Purpose of the Study:

• To develop a novel embedding method for the 1-RDM.
• To ensure N-representability and strong-orthogonality conditions for the embedded 1-RDM.
• To accurately compute total energies by treating kinetic energy exactly.

Main Methods:

• Partitioning the 1-RDM into domains.
• Describing each domain within the effective potential of others.
• Imposing N-representability and strong-orthogonality conditions.
• Approximating inter-domain correlations using density fluctuation couplings.
• Employing a corrected perfect-pairing functional for each domain.

Main Results:

• The proposed embedding reduced density matrix functional method (ERDMF) yields excellent results.
• The method accurately describes molecules with strong static intra-domain or dynamic inter-domain correlations.
• Kinetic energy is treated exactly, unlike in many density embedding methods.
• Weak overlapping of domain densities is not a requirement.

Conclusions:

• The ERDMF method offers a robust and accurate approach for electronic structure calculations.
• It is particularly effective for systems well-described by a single Lewis structure.
• This method advances the field of quantum embedding for 1-RDM.