Research

Electronic structure theory

It is the electronic states of materials that determine many of their physical and optical properties. The underlying fundamental equation governing the quantum mechanical behavior of electrons is the Schrödinger equation, which, however, is infeasible to solve even with the help of supercomputers. This limitation has led to the development of various approximations that have proven successful in qualitatively interpreting experimental results and theoretically predicting unknown compounds. Nonetheless, it is known that many commonly used theoretical calculation methods fail when the quantum mechanical behaviors of electrons become particularly pronounced, such as in radical organic molecules or transition metal complexes. In our group, we aim to develop novel theories that are effective for compounds where such electronic “quantum entanglement” is strong. By translating these theories into programs, we strive to pioneer uncharted areas of chemistry, thus reaching beyond the capabilities of existing methods.

Artificial water splitting

Artificial water splitting \({\rm H}_2{\rm O} \rightarrow {\rm H}_2 + \frac{1}{2} {\rm O}_2\), especially by sunlight, is expected as a promising clean energy technology. By efficiently converting solar energy into the chemical bond energy of hydrogen molecules, artificial photosynthesis would hold immeasurable industrial value. However, its commercial viability has been hindered by various challenges, such as the inefficient conversion of solar energy. The oxygen evolution reaction is an oxidation reaction involving four electrons in a stepwise manner, and new catalyst designs are needed to achieve this using visible light. We address this challenge by theoretically investigating catalysts and elucidating catalytic mechanisms through first-principles simulations.

Exploring applications of quantum computers

With the advancement of super computers, quantum chemical calculation has achieved significant success. However, to accurately simulate chemistry, which is governed by quantum mechanics, it is ideal to build a computer that operates based on the principles of quantum mechanics. This concept, proposed by Richard Feynman in 1982, has steadily progressed to this day and has been realized as quantum computers. However, current quantum computers have various limitations such as the significant influence of noise, making them still an evolving research field. In our group, we are interested in developing “quantum algorithms” necessary for effectively utilizing quantum computers, which are expected to revolutionize the paradigm of quantum chemistry in the future, with a medium to long-term perspective.