Efficient Implementation of Density Functional Theory Based Embedding for Molecular and Periodic Systems Using...

Area of Science:

• Computational chemistry
• Quantum mechanics
• Materials science

Background:

• Density functional theory (DFT) is a powerful tool for electronic structure calculations.
• Treating complex systems, especially those with both localized and delocalized electronic features, remains a challenge.
• Existing embedding methods often struggle to seamlessly integrate periodic and aperiodic components.

Purpose of the Study:

• To develop and implement a practical and effective DFT-based embedding scheme.
• To enable the simultaneous treatment of periodic and aperiodic systems.
• To facilitate high-level quantum mechanical calculations on specific regions of interest within larger systems.

Main Methods:

• Utilizing Gaussian basis functions for orbital and electron density expansion, enabling an all-electron direct-space representation.
• Implementing three embedding flavors: molecule-in-molecule, molecule-in-periodic, and periodic-in-periodic.
• Coupling the embedding scheme with correlated wave function theory (WFT) methods and developing real-time time-dependent DFT embedding theory (RT-TDDFET).

Main Results:

• The developed method effectively treats periodic and aperiodic systems on an equal footing, avoiding pseudopotentials.
• Accurate prediction of adsorption and excitation energies using WFT-in-DFT embedding.
• RT-TDDFET demonstrates accurate absorption spectra prediction for systems with uncoupled excitations.

Conclusions:

• The implemented DFT embedding scheme offers a versatile and efficient approach for studying complex molecular and material systems.
• This method allows for high-level electronic structure calculations on localized regions within extended environments.
• The successful application of WFT-in-DFT and RT-TDDFET highlights their potential for advancing research in low-dimensional systems and spectroscopy.