Combining Wave Function Methods with Density Functional Theory for Excited States.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Electronic structure methods are crucial for understanding molecular and material properties.
• Wave function theory (WFT) and density functional theory (DFT) are leading approaches with distinct strengths and limitations.
• Accurate modeling of excited-state chemistry remains a significant challenge.

Purpose of the Study:

• To provide a comprehensive review of state-of-the-art electronic structure methods.
• To discuss the advantages and disadvantages of WFT and DFT.
• To present modern hybrid approaches combining WFT and DFT for improved accuracy, especially for excited states.

Main Methods:

• Review of single-reference and multireference WFT methods.
• Analysis of various DFT approximations, including generalized Kohn-Sham (KS) theory, global, range-separated, and local hybrids.
• Exploration of methods combining DFT with many-body theory (e.g., GW approximation, Bethe-Salpeter equation) and multiconfigurational WFT.

Main Results:

• Discussion of the theoretical underpinnings and practical applications of combined WFT-DFT methods.
• Presentation of techniques for incorporating KS orbitals into many-body calculations and WFT frameworks.
• Overview of advancements in algorithms for accelerating GW calculations and modeling excited states.

Conclusions:

• Hybrid WFT-DFT methods offer promising avenues for overcoming the limitations of individual approaches.
• These combined methods are essential for accurate predictions of electronic and optical properties, particularly for excited states.
• Continued development in this area is vital for advancing computational chemistry and materials science.