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Proper theoretical descriptions of ground and excited states are critical for understanding molecular photophysics and photochemistry. Complex interactions in experimentally interesting molecular systems require multiple approximations of the underlying quantum mechanics to practically solve for various physical observables. While high-level calculations of small molecular systems provide very accurate excitation energies, this accuracy does not always extend to larger systems or other properties. Because of this, the “best” method to study new molecules is not always clear, leading many researchers to default to inexpensive and easy-to-use black-box methods. Unfortunately, even when these methods reproduce experimental excitation energies, it is not necessarily for the right reasons. Without accurate descriptions of the underlying physics, it becomes challenging to understand new classes of molecules. Consequently, predicted properties and their trends may not offer reliable mechanistic understanding. This review is targeted at beginners in computational chemistry who are interested in studying excited-state properties. A brief overview of common ground- and excited-state methods are covered for easy reference during the comparison of methods. The primary focus of this review is to compare the accuracy of these methods for several important classes of chromophores. The performance and accuracy of each method are explored to provide practitioners a road map on what methods work well for different molecular systems and identify further work that needs to be done in the field. 

Defects and dopants play critical roles in defining the properties of a material. Achieving a mechanistic understanding of how such properties arise is challenging with current experimental methods, and computational approaches suffer from significant modeling limitations that frequently require a posteriori fitting. Consequently, the pace of dopant discovery as a means of tuning material properties for a particular application has been slow. However, recent advances in computation have enabled researchers to move away from semiempirical schemes to reposition density functional theory as a predictive tool and improve the accessibility of highly accurate first-principles methods to all researchers. This Perspective discusses some of these recent achievements that provide more accurate first-principles geometric, thermodynamic, optical, and electronic properties simultaneously. Advancements related to supercells, basis sets, functionals, and optimization protocols, as well as suggestions for evaluating the quality of a computational model through comparison to experimental data, are discussed. Moreover, recent computational results in the fields of energy materials, heterogeneous catalysis, and quantum informatics are reviewed along with an evaluation of current frontiers and opportunities in the field of computational materials chemistry. 

The use of photoredox catalysis for the synthesis of small organic molecules relies on harnessing and converting the energy in visible light to drive reactions. Specifically, photon energy is used to generate radical ion species that can be harnessed through subsequent reaction steps to form a desired product. Cyanoarenes are widely used as arylating agents in photoredox catalysis because of their stability as persistent radical anions. However, there are marked, unexplained variations in product yields when using different cyanoarenes. In this study, the quantum yield and product yield of an α-aminoarylation photoredox reaction between five cyanoarene coupling partners and N-phenylpyrrolidine were characterized. Significant discrepancies in cyanoarene consumption and product yield suggested a chemically irreversible, unproductive pathway in the reaction. Analysis of the side products in the reaction demonstrated the formation of species consistent with radical anion fragmentation. Electrochemical and computational methods were used to study the fragmentation of the different cyanoarenes and revealed a correlation between product yield and cyanoarene radical anion stability. Kinetic modeling of the reaction demonstrates that cross-coupling selectivity between N-phenylpyrrolidine and the cyanoarene is controlled by the same phenomenon present in the persistent radical effect. 

An electron donor – acceptor (EDA) complex forms between 1,4-dicyanobenzene and N -phenylpyrrolidine, which are coupling partners for the α-aminoarylation photoredox reaction. Calculations and experiments demonstrate the EDA complex is a better base than N -phenylpyrroline. A re-analysis of the α-aminoarylation reaction suggests that the EDA complex is a proton acceptor in the reaction.