new carbon-based nano-functional materials First-principles study

　　Title: new carbon-based nano-functional materials First-principles study
　　Author: Zhang Zhuxia
　　Degree-granting units: Taiyuan University of Technology
　　Key words: maximum five-membered ring separation rules;; metal package within fullerenes;; carbon nanotubes;; graphene;; first principles
　　Abstract:
　　New Carbon features covering almost all the properties of matter on earth or even opposed to the two properties, from the most hard to very soft, full-absorption - all light, insulator - semiconductor - high conductor, insulation - good thermal conductivity, high-speed rail magnets, high critical temperature superconductors. Nano-carbon materials Rare earth magnets exhibit specific optical, electrical, magnetic, thermal, mechanical, mechanical and other properties, has become the world's scientific research hot spots. First-principles density functional theory based method does not rely on the experience of its parameters as condensed matter physics, quantum chemistry and materials science in the primary research tool. In this paper a number of different dimensions of the new nano-carbon-based materials, such as: fullerenes, carbon nanotubes, graphene and other research carried out first principles. Study as follows:
　　(1) were studied using density functional theory in line and do not meet the five-membered ring maximum separation rule (IPR) of Tb_3N @ C_ (84) isomers of a series of structural and electronic properties. The results show that there is a cage to the adjacent five-membered ring structure does not meet the IPR rules with the largest energy gap, showed the best kinetic stability; meet the IPR rules Tb_3N @ C_ (84) compounds have the best thermodynamic stability. Tb3N and C84 is the main force between the ionic bond, and Fermi surface Tb_3N @ C_ (84) than the C84 has a large electronic distribution, indicating Tb3N embedded can enhance the conductivity of the cage.
　　(2) using B3LYP/6-31G (d) method for organic solar cells as electron acceptor materials, fullerene derivatives phenyl C61 butyrate ([60] PCBM) of the isomers were calculations. PCBM and C60 through the six-membered ring and six-membered ring common to C = C double bond has been the product is a product of thermodynamic control; by five-membered ring and six-membered ring CC bond plus share of the product obtained is the dynamic control product. [60] PCBM and C_ (60) of the first adiabatic electron affinity is very close. PCBM on the frontier orbital contribution is small, [60] PCBM the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the electron cloud mainly in the cage. PCBM enhance the C_ (60) the level of the LUMO energy level, help to improve the photoelectric conversion efficiency of solar cells. Natural population analysis shows that between PCBM and cage no significant charge transfer. All studies have shown that PCBM group does not involve cell photoelectric conversion process, but the adjustment C_ (60) raise the level of photoelectric conversion efficiency levels play an important role. Use the same method also studied [70] PCBM, obtained the same pattern.
　　(3) First-principles study of Ag adsorption in the carbon tube wall and tube-side modification of carboxyl and hydroxyl groups on the load. The results show that the adsorption of Ag can be stable in the pipe wall, in a certain diameter range, the adsorption capacity as http://www.chinamagnets.biz/ the diameter increases. For Ag load in the modified-COOH and-OH groups on the SWCNT after when,-COOAg stability than-OAg. Whether it is a single modified-COOH or-OH group, or a total modification of-COOH and-OH groups, only the first Ag is stable chemical adsorption, after adsorption of Ag mainly in the form of physical adsorption in carbon nanotubes on the surface load . This experiment also shows from the side of Ag ions in the modified carbon nanotubes in the load is mainly dominated by physical adsorption.
　　(4) using density functional theory study of Au-doping atoms or modified graphene (graphene) and cysteine-binding ability and character. Au-S bond between the enhanced role of the graphene and the bonding between cysteine. Modified or doped with Au atom graphene, can increase the graphene substrate and electron transfer between cysteine, more electron transfer substrate graphene changed the nature of the vicinity of the Fermi level, changing the nature of the conductance of graphene. The results show that Au atoms modified or doped graphene is a potential detection of cysteine ​​sensor materials, in the detection of cysteine-rich metallothionein and other biological fields has been widely used. This is also the Pt-doped graphene has been studied, the results indicate that it is a good sensor material cysteine.
　　Degree Year: 2010