Our research focuses on an understanding of electronic structures and magnetic properties of molecule based magnetic materials and quantum manipulation of the electronic spin structures for the application to quantum computer/quantum information science which have been rapidly growing up. On the basis of the electronic structures we are developing the theory of molecular design of molecule-based multi-spin systems. Molecular systems applied are a wide range from organic high-spin systems to inorganic polynuclear complexes. The organic systems include polyradicals, poly-carbenes and nitrenes, and the polyionic states of the organic molecules.
Continuous wave/pulsed electron magnetic resonance (EMR) spectrometers are major research resources used to microscopically elucidate the electronic structures of magnetic materials. Various advanced EMR techniques such as single crystal EMR, electron multiple resonance (ENDOR/TRIPLE, ELDOR-NMR, and ELDOR), and high-field/frequency EMR, are applied to the magnetic materials. Pulsed EMR experiments are also performed to obtain information about the magnetic materials in time domain. A multidimensional EMR method by various pulse sequences on the pulsed EMR experiments sometimes makes spectral assignments easier. Methodological developments in EMR spectroscopy are also important research themes for applying the sophisticated molecule-based magnetic materials. The two-dimensional electron spin transient nutation (ESTN) method based on pulsed EMR was developed in order to identify molecular spin multiplicity of the high-spin systems and to discriminate high-spin species in mixed spin systems. The 2D-ESTN method is based on pulsed electron magnetic resonance to measure the spin Hamiltonian in terms of the rotating frame. This method is capable of discriminating high-spin species by differences in the transition moment. 2D-ESTN spectroscopy is classified as a new type termed transition moment spectroscopy. The EMR techniques are valuable tools for studying the electronic structures of molecule-based magnetic materials.
Computational chemistry is another resource available to study the electronic structures of magnetic materials. Ab initio and density functional calculations are used to understand the magnetic materials. We consider the electronic structures of these materials theoretically in terms of modern computational chemistry, and are also interested in the evaluation of magnetic parameters of the high-spin systems. The evaluation of fine structure parameters of delocalized high-spin systems is one of the most difficult issues. We are trying to elucidate new findings from both experimental and theoretical views.