Ab-Initio Quantum Simulation of Electoronic Dynamics in Finite Electron System

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We have developed a quantum mechanical and first principle simulation for electronic dynamics based on the time-dependent density-functional theory ,(TD-DFT). The time-dependent Kohn-Sham equation, which is a basic equation in the TD-DFT, is solved in real-space and -time for this purpose. Results of the present research project are summarized as follows :1. Electronic excitations and optical responses of various moiecuies and atomic clusters are investigated. In particular, a new numerical method for nonlinear optical responses (molecular hyperpolarizabilities and two-photon absorption ) is developed. A theory to describe coupling with continuum states is developed as well, and is applied to optical absorptions of molecules in the vacuum ultraviolet region.2. A real-time and real-space method is developed for the dielectric functions ol periodic solid. The method has been applied to a simple metal and an insulator, and is planned to be extended to carbon nanotubes.3. The applicability of the TD-DFT for electron-vibration coupling is examined taking optical absorption spectrum of benzene molecule as example.3. Multiple electron transfer processes in the ion-atomcollision are described. This helpedus obtaining adeeper understanding on themechanisms of electron transfer.5. Research on ionization mechanism of atoms and molecules in a strong laser field is initiated.6. A theoretical framework for atomic spectra in the liquid helium is developed.7. We have prepared FORTRAN code of optical responses in the TD-DFT, and have been distributing it to those who are interested in using our method.