Density Matrix Embedding Pair-Density Functional Theory for Molecules.

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Theoretical Chemistry

Background:

• Strong electron correlation effects in finite systems pose significant computational challenges.
• Accurate modeling of these systems is crucial for understanding chemical reactivity and material properties.

Purpose of the Study:

• To develop and validate a computationally efficient method for studying localized strong electron correlation.
• To introduce density matrix embedded pair-density functional theory (DME-PDFT) as a cost-effective alternative to traditional methods.

Main Methods:

• Combining Density Matrix Embedding Theory (DMET) with Multiconfiguration Pair-Density Functional Theory (MC-PDFT) to create DME-PDFT.
• Comparing DME-PDFT with second-order n-electron valence state perturbation theory within DMET (NEVPT2-DMET).
• Validating methods through calculations on methyl diazine bond dissociation and a Fe(H2O)62+ complex spin-splitting energy gap.

Main Results:

• DME-PDFT significantly reduces computational cost compared to nonembedded MC-PDFT.
• DME-PDFT exhibits faster convergence towards nonembedding limits than NEVPT2-DMET.
• Embedding schemes demonstrate higher accuracy than truncation schemes for undercoordinated transition metal complexes.

Conclusions:

• DME-PDFT is a promising and efficient method for investigating electron correlation in finite systems.
• The developed methodology provides a valuable tool for computational chemistry and materials science.
• Embedding schemes offer superior accuracy over truncation for specific complex systems.