FPS Research-Electron Dynamics

Carbon nanotubes have attracted great attention because of their potential application to electronic nanodevices utilizing the multiplicity of transport property due to their topological structures. Nanopeapods containing of fullerene arrays inside single-wall carbon nanotubes have been reported.
We investigated transport properties of various C60@ (10,10) [a (10,10) nanotube encapsulating C60 molecules] systems by varying the distribution of C60s in the nanotube. The periodic C60@ (10,10) systems exhibit quantized transmission corresponding to their band structure. The transport properties of C60@ (10,10) are found to significantly depend on the density of C60s in the nanotube. We also investigated the transport properties of C60@ (10,10) systems without periodicity.
In this study, we employ the Green’s function method with the realistic tight-binding model taking account of carbon 2s and 2p atomic orbitals. For this method, see the website http://www.ciss.iis.u-tokyo.ac.jp/rss21/index.html.

Nanoscale devices constructed from molecules with some functions are candidates for units of electronic circuits in the future. It is well known that molecular functions depend on not only materials but also molecular structures and contact structures between molecules and electrodes.
For example, the transport properties of a junction system of a biphenyl-dithiol molecule are studied. The transmission of this junction system is widely varied by about 100 times, depending on the dihedral angle between the two phenyl rings. The possibility of a molecular switch utilizing this characteristic is discussed.
In this study, we employ the non-equilibrium Green’s function (NEGF) method based on a density functional theory. For the detail of this method, see the website http://www.ciss.iis.u-tokyo.ac.jp/rss21/index.html.

Using a formalism based on the real-time propagation time-dependent density functional theory (RTP-TDDFT), we have investigated the mechanisms of the photoinduced structural transformations of molecular systems on the femtosecond scale. We have shown that the RTP-TDDFT formalism can reproduce the vibration frequencies in the excited state. This project was done in collaboration with Dr. Y. Miyamoto (Nano Electronics Res. Labs., NEC). The code 'FPSEID' he develoved was used in this work. Further works are being done in Computational Physical Chemistry (CPC) team (organised by Dr. Tateyama) in WPI-MANA, NIMS. Visit the MANA-CPC web page.

We have developed a DFT-based ab initio free energy calculation method for change of chemical bonds coupled to electron transfer by combining constrained molecular dynamics with the energy gap method
for redox free energy. Further works are being done in Computational Physical Chemistry (CPC) team (organised by Dr. Tateyama) in WPI-MANA, NIMS. Visit the MANA-CPC web page.

Research Index