Theoretical Characterization of Chiral Carbon Nanotube Encapsulating Ellipsoidal C70

The molecular orientation of ellipsoidal C-70 in carbon nanotubes is carefully studied by first principles calculations. Using (14, 7) single-wall carbon nanotube (SWCNT) as a prototype material, we explored that the weak chemical interaction between SWCNT and C-70 was the crucial factor to determine the molecular orientation. However, the small energy difference makes the distinguishment of two possible molecular orientations difficult. By simulating scanning tunneling microscope images and optical properties, we found that local electronic states sensitively depended on the molecular orientation of ellipsoidal C-70, which provided a practical way of using scanning tunneling microscope to recognize the molecular orientation of ellipsoidal C-70.