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Department of Complex Systems Science

IUCHI, Satoru
Material Informatics Group
Assistant Professor
Dr. of Science
Research Field
Theoretical/Computational Chemistry

Current Research

Theoretical Study on Dynamics of Molecular Systems in Solutions
My research activities have focused on various chemical phenomena in solutions and interfaces using methods in theoretical/computational chemistry such as electronic structure theory and molecular dynamics simulation. In particular, I have utilized computer simulation techniques with realistic molecular models which accurately describe intermolecular interactions in the condensed phase. I have also been interested in building new molecular models on the basis of electronic structure calculations. 

(1) Many-body electronic polarization effects in aqueous solutions
It has been pointed out that the inclusion of many-body electronic polarization effects in the intermolecular potential function is necessary to achieve an accurate description of condensed phase environments. We have thus developed a new polarizable water model using the charge response kernel formalism and have shown, for example, that polarization effects are important in describing vibrational spectral shapes related to the water hydrogen bond network. We have also shown through the force-matching method that polarization effects can be effectively mapped into the pairwise potential functions for various properties of liquid water and of the water-vapor interface. The results and implications obtained from these works will be utilized in future MD simulation studies.

(2) Hydrated excess proton at water-hydrophobic interfaces
Studying the behaviors of ions at water-hydrophobic interfaces is important for understanding various chemical processes in heterogeneous environments such as atmospheric aerosols and biological systems. We have analyzed the behavior of the hydrated excess proton at various water-hydrophobic interfaces in a systematic fashion through molecular dynamics simulations, where the inherent delocalized nature of the excess proton is taken into account by using the MS-EVB model. Based on an analysis of the free energy profiles, we have investigated the thermodynamic driving forces which determine the surface preference of the excess proton.

(3) Electronic excited state dynamics of transition metal ion aqueous solution
Our understanding of electronic excited state dynamics in solutions and biological systems is still limited. We have investigated the electronic relaxation dynamics of Ni2+ ion in aqueous solution. In order to describe the potential energy surfaces of the Ni2+ ion in aqueous solution, we have developed a new model Hamiltonian which is sufficiently simple to allow adiabatic and non-adiabatic simulation studies of electronic excited states in bulk aqueous solutions. The results show that fast non-adiabatic transitions occur among the first three excited states and a slow transition to the ground state, which was consistent with data from a time-resolved experiment.

My current research activities have mainly focused on photochemical processes of transition metal (TM) complexes in solutions. The rich electronic structures of TM complexes are of interest because of their importance for applications in molecular devices and photochemistry. Therefore, a detailed understanding of the electronic structures of TM complexes is desirable in order to design and control useful materials. On the experimental front, ultrafast electronic relaxation processes have been investigated for prototype TM solution systems. On the theoretical front, however, studies on the excited-state dynamics of TM systems are still limited mainly because high-level electronic structure calculations are required in order to describe the excited states of TM complexes. I am thus developing molecular models which can be used for simulation studies even of bulk solutions. My plan is to perform molecular dynamics simulations using molecular models thus developed, and to investigate various chemical processes of TM complexes in solutions such as nonradiative transitions, photoluminescences, vibrational relaxations, energy transfers, and energy dissipations.


  • 2005, March Dr. of Science, Kyoto University, Department of Chemistry.
  • 2005, June Postdoctoral Researcher, University of Utah.
  • 2008, August Program-Specific Researcher, Kyoto University, Department of Molecular Engineering.
  • 2008, October Program-Specific Research Center Assistant Professor, Kyoto University, iCeMS.
  • 2009, April Program-Specific Assistant Professor, Kyoto University, Department of Molecular Engineering.
  • 2010, April Assistant Professor, Nagoya University, Graduate School of Information Science.

Academic Societies

  • Chemical Society of Japan, Japan Society for Molecular Science.


  1. S. Iuchi, A. Morita, and S. Kato, “Molecular Dynamics Simulation with the Charge Response Kernel: Vibrational Spectra of Liquid Water and N-Methylacetamide in Aqueous Solution”, J. Phys. Chem. B 106, 3466-3476 (2002).
  2. S. Iuchi, A. Morita, and S. Kato, “Electronic relaxation dynamics of Ni2+-ion aqueous solution: Molecular-dynamics simulation”, J. Chem. Phys. 123, 024505(1-11) (2005).
  3. S. Iuchi, H. Chen, F. Paesani, and G. A. Voth, “Hydrated Excess Proton at Water-Hydrophobic Interfaces”, J. Phys. Chem. B 113, 4017-4030 (2009).