Theoretical Investigation For Bi-doped C Clusters,Tubelike Isomer Of As_n/Bi_n And A New Class Of B Nanotube

In the last few years, there has been great interest in producing new materials composed of transition metals and carbon due to their potential for use as catalysts, semiconductors, and superconductors, and in the quantum devices. The research of the C clusters set the stage for the studies of carbon fullerenes and nanotubes. In addition, the study of the structures and reactivity of metal carbides is also important for surface chemistry, combustion chemistry, and astrochemistry.A systemic study of the heavy element Bismuth-doped carbon clusters BimCn (n=1-20, m=1, 2) has been performed with all-electron density functional theory (DFT) method based on previous investigations of TMC_n, several properties including evolution of equilibrium geometries, electronic states, magnetic properties have been investigated; A class of inorganic metallocene sandwich clusters Fen(C₆)_n+1, Run(C₆)_n+1 and Crn(P₆)_n+1 have been designed and their electronic structures, magnetic moments have also been caculated; A series of hollow tubelike configurations Bi_n (n=30, 40, 50, 60, 70, 80, 90, 100) and As_m (m=30, 40, 50, 60) have been constructed, the stablity and electronic properties of tubelike Bin/Asm structures have been investigated in detail. The results show:(1) The small clusters BiCn appears the similar structural evolution to the Bi₂C_n: both BiC_n (n=1-9, 11, 12) and Bi₂C_n (n=1-12) always prefer to forming linear structures with the Bi atom bonded at one end or two ends; for the intermediate clusters BiC_n(n=10,13-19), the most energetically preferred configurations are ring planar structures. In the case of BiC20, the graphitic sheets are more stable than any of the other isomers.(2) The Bi atom doping C_n clusters does not always improve the host clusters stability, but the chemical activity become stronger. Mulliken population analysis indicate that Bi atom has positive charge population, suggesting that charge always transfers from Bi atom to C atoms. The total magnetic moment of BiCn is invariably 1μB, while that of Bi2Cn reveals an even-odd alternation effect, TMM of both BiCn and Bi2Cn are mainly located on the Bi sites.(3) The calculation results of multidecker sandwich clusters Fen(C₆)_n+1, Run(C₆)_n+1 and Crn(P₆)_n+1 indicate that Fe(C₆)₂,Ru(C₆)₂ and Cr₂(P₆)₃ are very stable and might serve as a small building block in nanodevice design assemblies. The Fe (Ru) atoms hold positive charge population in the Fen(C₆)_n+1 (Run(C)6)_n+1), while Cr atom have negative value in the Crn(P₆)_n+1. The quenching of the total magnetic moments have been found in the Fen(C₆)_n+1 and Run(C)6)_n+1 except Ru3(C6)4, meanwhile the normal and staggered sandwich clusters Crn(P6)n+1 also appear nonmagnetic.(4) With the increase of tube-like configurations sizes, the two classes of BiNTs and AsNTs appear semiconductive properties. Both the total spin magnetic moments of BiNTs (AsNTs) and the local spin magnetic moments of Bi (As) atom are zero; The density surface shows covalent bonding between Bi (As) atoms, average Mayer bond orders suggest that the covalence bonds slowly weaken with the increase of sizes; The HOMOs and LUMOs display sp³-like hybridization, which are mainly comprised of theσandÏ€orbitals.(5) The calculation results of the new class of Boron sheet and a series of Boron nanotubes show that both Boron sheet and Boron nanotubes are all stable and appear good metallic properties and characteristics of electronic transmission, except for the chiral vector (-12, 4) nanotube, for which there is an indirect gap of 0.31 eV.