Review makes connections between electron density-based methods

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Researchers have published a comprehensive review in Chemical Reviews on electron density-based methods.

Electron density topology is a concept of theoretical chemistry but there is nothing theoretical about the impact it has on the world around us and on applied research—it defines the type and properties of all chemical bonds, it allows explaining phenomena in a reality-anchored framework because electron density is a physical observable, and it allows constructing simulation methods that are expected to revolutionize computational materials science in the coming decades.

It was about 100 years ago that the modern concept of chemical bonding began to be formed, when Pauling first described chemical bonds from a quantum mechanical perspective. It took decades since then to develop tools and methods to measure, compute, and analyze electron density with a level of detail allowing quantitative conclusions.

While major advancements in the ways electron density is analyzed happened in the late 20th century (collectively known as QTAIM, quantum theory of atoms-in-molecules), it was not until this century that the toolbox was enriched with next-generation (NG) QTAIM (developed by one of the co-authors) allowing better insight into phenomena such as those happening at the femtosecond scale in matter under irradiation.

Importantly for present-day technology development, in particular of electrochemical power sources such as batteries, electron density analysis allows a reality-anchored description of mechanisms of redox reactions which is—as was shown by some of the co-authors—free of some of the blind spots of the familiar oxidation states ideology, for example, when describing a phenomenon known as "oxygen redox" which is actively researched for the development of high-capacity metal-ion batteries.

Electron-density based methods are also at the core of computational materials science, in particular, the widely used method called DFT (density functional theory) which is used to compute material structures, properties, and mechanisms of phenomena. Unfortunately, the DFT method as currently used in applications is too computationally costly to be applied at realistic length scales.

It is recent developments in density topology-based methods, combined with machine learning, including those by some of the co-authors, that should permit in near future large-scale DFT simulations and analysis of mechanisms of reactions, of excitations by light, etc. from a purely electron-density based framework.

The review, authored by an international team, was spearheaded by researchers from Institute of Science Tokyo (Sergei Manzhos and Manabu Ihara of the Ihara-Manzhos lab) and included collaborators from Canada (Paul Ayers of McMaster University and Cherif Matta of Mount Saint Vincent University), China (Samantha Jenkins of Hunan Normal University), and the U.S. (Michele Pavanello from Rutgers University). The project also saw significant contributions from young researchers, Daniel Koch from Canadian INRS and Xuecheng Shao from Rutgers University.

The review by Koch and collaborators does more than just review a field, it connects the dots between subfields that have largely developed in parallel, charting promising directions for future research that will allow more realistic computing and understanding of matter and phenomena.

More information: Daniel Koch et al, The Analysis of Electron Densities: From Basics to Emergent Applications, Chemical Reviews (2024). DOI: 10.1021/acs.chemrev.4c00297

Journal information: Chemical Reviews

Provided by Institute of Science Tokyo