Microscopic Tunneling Properties of Exotic Surfaces

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Research item 'electronic states of fullerene derivatives': By calculating from the first-principle, we explain STM images of 1,2,3 and 6 impurity pentagons in carbon sheet. Calculation of 1 pentagon system reproduces STM images. For 2 pentagons, HOMOs quite resemble to those of C60 molecule on Si(001)2×1 surface. For 3 pentagons, they also resemble to those of C60 on Si(111)7×7 surface.Impurity 6 pentagons is the model of the tip of carbon nanotube (CNT). Although many researchs of electronic states of CNT have been done over the world, the tip ends of all of CNT are 'open'. From the view point to utilize CNT for STM tip, we obtain electronic states of tip apex of 'closed' CNT. We have two types of CNT : arm-chair (C60) and zig-zag (C80). if pentagons of multi zig-zag CNT are arranged stellately, HOMOs have high charge density around 6 pentagons. Thus, we can reproduce field emission microscope (FEM) images which are obtained quite recently at Mie and Waseda Universities.Research item 'basic theory of field emission': By the complete set of above mentioned first-principle calculation, we get Green function, solve numerically Lippmann-Schwinger integral equation, and get the wavefunction of emitted electron. We apply to CNT and compare with FEM images.