Computational strategies for modelling excited states in organometallic chemistry

This chapter explores advanced computational methods and strategies to model excited states in organometallic systems, essential for advancing discovery, design, and comprehension in fields such as photocatalysis, artificial photosynthesis, and light-responsive materials. We initiate with a fundamental discussion on available quantum mechanical approaches for organometallic compounds, stressing the importance of carefully choosing theoretical methods that are specifically suited to their unique characteristics. We delineate the theoretical underpinnings and practical applications of various electronic structure methods, including density functional theory (DFT) and post-Hartree–Fock approaches, and detail their adaptability to the unique properties of transition metal complexes. Particular attention is given to multireference and perturbative methods, which are critical for accurately describing the complex electronic structure typical of organometallic compounds. Through hierarchical classification, critical evaluation, and carefully curated references, this chapter serves as both a primer and a deep dive into the computational toolbox available for organometallic researchers, offering insights into method selection and application challenges.