2024 marks an important milestone with the publication of a comprehensive review in Chemical Reviews on electron density-based methods. The review, authored by an international team, was spearheaded by leading 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 USA (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.
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 is about 100 years ago - around the time when Chemical Reviews was established (in 1924) - that the modern concept of chemical bonding began to be formed, when Pauling first described chemical bonds from 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 of Koch et al. did more than just review a field, it connected the dots between subfields that heretofore largely developed in parallel, charting promising directions for future research that will allow more realistic computing and understanding of matter and phenomena.
Dr. Manzhos says, "Year 2024 marks the 100th anniversary of the establishment of Chemical Reviews - an ACS journal that publishes only comprehensive and authoritative reviews in various areas of chemistry. Reviews of reference quality written - by invitation only - by experts who possess the bird's eye view and depth of expertise necessary to overview a field and to identify results that have potency for the future. The high regard in which the journal is held by the scientists is reflected in its hefty impact factor of 51. I am honored to have been featured."
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About Institute of Science Tokyo
Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of "Advancing science and human wellbeing to create value for and with society.
