Projection-Based DMRG-in-DFT Embedding Corrected by Nonadditive Exchange-Correlation.

Area of Science:

• Quantum chemistry
• Computational materials science
• Electronic structure theory

Background:

• Density functional theory (DFT) is widely used for chemical system analysis.
• Wave function in DFT (WF-in-DFT) embedding enhances DFT accuracy for complex systems.
• Density matrix renormalization group (DMRG) is effective for strongly correlated molecular fragments.

Purpose of the Study:

• To improve the accuracy of the DMRG-in-DFT method.
• To address limitations in describing the coupling between active components and their environment.
• To enhance the prediction of energetics and properties in strongly correlated chemical systems.

Main Methods:

• Combining exact exchange to minimize nonadditive exchange errors.
• Implementing a multireference adiabatic connection (AC) scheme to recover nonadditive correlation.
• Applying the improved DMRG-in-DFT embedding to strongly correlated systems.

Main Results:

• The accuracy of DMRG-in-DFT was primarily limited by approximate nonadditive exchange-correlation functionals.
• The refined method successfully reduced nonadditive exchange and correlation errors.
• Accurate predictions were achieved for H20 chain dissociation and C≡N bond cleavage.

Conclusions:

• The improved DMRG-in-DFT approach offers enhanced accuracy for strongly correlated systems.
• Refining the treatment of environmental coupling is crucial for embedding methods.
• This work provides a more reliable computational tool for complex chemical problems.