Modern multireference methods and their application in transition metal chemistry

Area of Science:

• Quantum chemistry
• Theoretical chemistry
• Computational chemistry

Background:

• Transition metal chemistry presents significant challenges for quantum chemical methods.
• The presence of static and dynamic electron correlation effects complicates accurate calculations.
• Wavefunction-based multireference (MR) methods offer a robust approach but face high computational costs and conceptual difficulties.

Purpose of the Study:

• To review recent advancements in multireference electronic structure methods.
• To discuss the opportunities and challenges these advancements present for transition metal chemistry.
• To highlight the importance of active space selection in these methods.

Main Methods:

• Exploration of modern selected configuration interaction (CI) methods.
• Application of Full-Configuration Interaction Quantum Monte Carlo (FCIQMC) for approximate Full-CI solutions.
• Utilizing the Density Matrix Renormalization Group (DMRG) for efficient electronic structure calculations.
• Focus on the development of active space selection techniques.

Main Results:

• New computational methods significantly reduce the cost of solving the Full-Configuration Interaction (Full-CI) problem.
• These advancements extend the applicability of multireference methods to larger and more complex systems.
• Development of numerous selection aids for defining adequate active spaces.

Conclusions:

• Recent computational breakthroughs enhance the capability of theoretical studies in transition metal chemistry.
• Efficient active space selection is crucial for the success of modern multireference methods.
• These advancements pave the way for more accurate and feasible quantum chemical investigations of transition metal systems.