Theoretical Study of Novel Structures of Materials by Electronic Excitation and Unified Model

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1) A variety of possible configurations of metastable structures has been calculated and proposed for s-p bonding materials, especially on nano-size cluster systems, surfaces, point defects and amorphous states. The relations among them and also between that of bulk system are clarified. The co-doping method is proposed for p- or n-type valence control of wide gap semiconductors.2) Theories for optical processes are developed for semiconductor hetero interfaces and surfaces, and for one-dimensional and mesoscopic organic materials.3) A general theory is proposed for the transition of electronic-atomic systems both describing the static limit (tunnel process) and the dynamical limit (level crossing). The mechanisms are proposed for the desorptin of an adatom on a semiconductor surface and also for the atom manipulation by a tip of STM.4) Nonmetallic crystalline materials are classified into five types, F,SI,SII,SIII,and U,according to the character of a relaxd photo-created exciton, the degree of the lattice relaxation and the way of exciton annihilation.In order to understand completely the structural change by electronic excitation in condensed matter, it is necessary to know (a) the character of the ground state (atomic configuration and electronic state), (b) the way of excitation (by photon or high energy particle ; valence excitation or core excitation) and the character of the electronic excited state, (c) the relaxation path in space and time and (d) the character of the relaxd excited state. The investigation of each mechanism and their unification enable us to understand deeply the bondings of condensed matter and have a guiding principle to fabricate novel structures of materials.