Choosing closed-ended armchair （5, 5） single-wall carbon nanotubes （CCNTs） as electrodes, we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspen...Choosing closed-ended armchair （5, 5） single-wall carbon nanotubes （CCNTs） as electrodes, we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes. It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CF1 and double-bonded models： the conductances of C20 dimers are markedly smaller than those of monomers. The physics is that incident electrons easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions. Moreover, we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally. The bonding property of the molecular junction with configuration CF1 has been analysed by calculating the Mulliken atomic charges. Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones, leading to the fact that N-doped junctions have relatively large conductance.展开更多
By using open-ended armchair （6, 6） single-wall carbon nanotubes as electrodes, we investigate the electron transport properties of an all-carbon molecular junction based on the C82 molecule. We find the most stable...By using open-ended armchair （6, 6） single-wall carbon nanotubes as electrodes, we investigate the electron transport properties of an all-carbon molecular junction based on the C82 molecule. We find the most stable system among different isomers by performing structural optimization calculations of the Cs2 isomers and the C82 extended molecules. The calculated results show that the C82 -C2 （3） isomer and the C82 extended molecule with C82-C2 isomer are most stable. For the all-carbon hybrid system consisting of C82-C2 extended molecules, it is shown that the Landauer conductance can be tuned over several orders of magnitude both by changing the distance between two electrodes and by changing the orientation of the C82 molecule or rotating one of the tubes around the symmetry axis of the system at a fixed distance. Also, we find the most stable distance between two electrodes from the total energy curve. This fact could make this all-carbon molecular system a possible candidate for a nanoelectronic switch. Moreover, we interpret the conductance mechanism for such a molecular device.展开更多
Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation en...Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 50504017.
文摘Choosing closed-ended armchair （5, 5） single-wall carbon nanotubes （CCNTs） as electrodes, we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes. It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CF1 and double-bonded models： the conductances of C20 dimers are markedly smaller than those of monomers. The physics is that incident electrons easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions. Moreover, we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally. The bonding property of the molecular junction with configuration CF1 has been analysed by calculating the Mulliken atomic charges. Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones, leading to the fact that N-doped junctions have relatively large conductance.
基金Supported by the National Natural Science Foundation of China under Grant No 50504017.
文摘By using open-ended armchair （6, 6） single-wall carbon nanotubes as electrodes, we investigate the electron transport properties of an all-carbon molecular junction based on the C82 molecule. We find the most stable system among different isomers by performing structural optimization calculations of the Cs2 isomers and the C82 extended molecules. The calculated results show that the C82 -C2 （3） isomer and the C82 extended molecule with C82-C2 isomer are most stable. For the all-carbon hybrid system consisting of C82-C2 extended molecules, it is shown that the Landauer conductance can be tuned over several orders of magnitude both by changing the distance between two electrodes and by changing the orientation of the C82 molecule or rotating one of the tubes around the symmetry axis of the system at a fixed distance. Also, we find the most stable distance between two electrodes from the total energy curve. This fact could make this all-carbon molecular system a possible candidate for a nanoelectronic switch. Moreover, we interpret the conductance mechanism for such a molecular device.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10325415 and 50504017)the Natural Science Foundation of Hunan Province,China(Grant No.07JJ3102)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department,China(Grant No.10C1171)the Science Development Foundation of Central South University,China(Grant Nos.08SDF02 and 09SDF09)
文摘Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.
