Research
My research focuses on developing computational methods to investigate the chemical evolution of the universe. By uncovering fundamental reaction mechanisms and molecular processes across diverse astrophysical environments, I aim to gain our understanding of complex organic molecule synthesis and its connection to prebiotic chemistry, providing deeper insights into the origins of life in the universe.
Software
QM/MM: PyQMMM, SICTWO
Electronic structure: Gaussian16, ADF, ORCA
Molecular dynamics: DFTB, TINKER
Periodic DFT: ADF-BAND
Computing
In-house servers:
HPE ProLiant DL360 Gen10 | 40, 64, or 80 CPUs | 256 GB or 320 GB memory | 1.2 TB HDD.
Supercomputers:
C3SE (Gothenburg)
ICR (Kyoto)
Development of computational methods
The chemical reactions are very fast processes (i.e., fs scale), and the lifetime of the intermediates is very short. Therefore, experimental characterisation of the atomic-scale chemical processes is challenging. Modern quantum chemical methods, employing ab-initio computations, offer a way to overcome these limitations. In this direction, I develop an Unbiased Reaction Path Search (URPS) approach to study complex molecular systems. My current focus is to combine URPS approach with a neural network, the so-called Artificial Intelligence-Guided Reaction Path Refinement Algorithm (AI-RPRA) to determine complex molecular structures or complex reaction mechanisms.
Also, I develop quantum mechanics/molecular mechanics (QM/MM) methods. In the QM/MM approach, the electronically important part of the molecular system is calculated using a QM method, while the remaining part is calculated using a MM method. The polarizable force fields are an advanced type of computational model used in QM/MM calculations to accurately simulate molecular interactions by incorporating the ability of atoms to change their electronic distributions in response to their environment. The QM/MM implementation in the in-house PyQMMM and SICTWO programs supports various modern polarizable and non-polarizable force fields.
Origin of life in the Universe
Radical-driven reactivity: More than 300 molecules have been found in the interstellar medium (ISM). However, the origin of the molecules in the ISM and the chemical evolution in the Universe that leads to the origin of life are unknown. One of the plausible theories for the origin of molecules in the ISM is the radical-driven chemistry of ice dust particles. Further, the molecular building blocks of the molecules in the ISM, particularly small radicals may adsorb on the interstellar ice grains in the ISM, diffuse, and react at low temperatures (e.g., 10 K). These chemical processes are not fully rationalized. I use computational methods to determine reaction mechanisms for the synthesis of biologically relevant molecules (E.g., amino acids, sugars) in the ISM.
Anion-driven reactivity: My recent ab-initio computations showed the effectiveness of the OH- (anion) diffusion via the proton hole transfer in ice at low temperatures. Thus, driving the OH- (anion) in ice bulk increases the possibility of reacting with the molecules trapped in ice and opens the OH- (anion)-driven reactivity to synthesize molecules in the interstellar ice bulk at low temperatures. I aim to establish anion-driven reactivity using the URPS scheme to determine known, unknown, and unexpected anion-driven reaction mechanisms to construct chemical networks.
Current collaborations: Francois Dulieu (CY Cergy Paris Université), Yasuhiro Oba and Naoki Watanabe (Hokkaido)
Design novel catalysis
Transition metal clusters serve as catalytic agents in early Earth chemistry, driving chemical transformations essential for the emergence of life. These systems can activate and transform small molecules, such as N₂, CO₂, and CH₄, under prebiotic conditions, enabling the synthesis of complex organic frameworks. Quantum chemical investigations of synthetic transition metal clusters provide a fundamental understanding of their electronic structure, reactivity, and catalytic mechanisms. My goal is to design novel catalysts for sustainable technologies.
Current experimental collaborations: Yasuhiro Ohki (Kyoto), Pedro J. Perez (Huelva), Masaharu Nakamura (Kyoto).