Development and Application of the ONIOM Method. Development
of a multi-layered method called ONIOM, a method integrating different
levels of molecular orbital methods and molecular mechanics methods
for accurate theoretical calculations for large molecular systems.
Studies of Molecular Interactions. The first ab initio
calculation and prediction of the structure of water dimer in
1968. Development of the energy decomposition scheme for analysis
of intermolecular interactions, including hydrogen bonding, electron
donor-acceptor interaction, and metal-ligand interaction.
Studies of Potential Energy Surfaces for Chemical Reactions.
The first application of ab initio gradient to the transition
state and the intrinsic reaction coordinate. The method of finding
the lowest point on the crossing seam of potential surfaces. Studies
of potential surfaces and elucidation of reaction mechanisms,
in both ground and excited states. Major studies include CH3I
photodissociation, ion-molecule reactions, and reactions in clusters.
Structure, Interactions and Reactions
of Nano Structures. Theoretical studies of the mechanism
of formation of fullerenes from small carbon clusters such as
C2. Structure and vibrational
spectra of nanotubes using ONIOM and other methods.
Studies of Structure and Reactions of Transition Metal Complexes.
The first determination of the transition state for elementary
organometallic reactions. The first to find the electronic origin
of agostic interaction. The first to calculate the potential energy
profile of an entire catalytic cycle. Major contributions to elucidation
of reaction mechanisms of many organometallic reactions and homogeneous
catalyses as well as metalloenyme reactions.