The conductance stabilities of carbon atomic chains （CACs） with different lengths are investigated by performing the- oretical calculations using the nonequilibrium Green＇s function method combined with density fun...The conductance stabilities of carbon atomic chains （CACs） with different lengths are investigated by performing the- oretical calculations using the nonequilibrium Green＇s function method combined with density functional theory. Regular even-odd conductance oscillation is observed as a function of the wire length. This oscillation is influenced delicately by changes in the end carbon or sulfur atoms as well as variations in coupling strength between the chain and leads. The lowest unoccupied molecular orbital in odd-numbered chains is the main transmission channel, whereas the conductance remains relatively small for even-numbered chains and a significant drift in the highest occupied molecular orbital resonance to- ward higher energies is observed as the number of carbon atoms increases. The amplitude of the conductance oscillation is predicted to be relatively stable based on a thiol joint between the chain and leads. Results show that the current-voltage evolution of CACs can be affected by the chain length. The differential and second derivatives of the conductance are also provided.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304079,11404094,and 51201059)the Priority Scientific and Technological Project of Henan Province,China(Grant No.14A140027)+1 种基金the School Fund(Grant No.2012BS055)the Plan of Natural Science Fundamental Research of Henan University of Technology,China(Grant No.2014JCYJ15)
文摘The conductance stabilities of carbon atomic chains （CACs） with different lengths are investigated by performing the- oretical calculations using the nonequilibrium Green＇s function method combined with density functional theory. Regular even-odd conductance oscillation is observed as a function of the wire length. This oscillation is influenced delicately by changes in the end carbon or sulfur atoms as well as variations in coupling strength between the chain and leads. The lowest unoccupied molecular orbital in odd-numbered chains is the main transmission channel, whereas the conductance remains relatively small for even-numbered chains and a significant drift in the highest occupied molecular orbital resonance to- ward higher energies is observed as the number of carbon atoms increases. The amplitude of the conductance oscillation is predicted to be relatively stable based on a thiol joint between the chain and leads. Results show that the current-voltage evolution of CACs can be affected by the chain length. The differential and second derivatives of the conductance are also provided.
