title: Changes of coupling between the electrodes and the molecule under external bias bring negative differential resistance.
abstract: We report a first-principles study of electrical transport and negative differential resistance (NDR) in a single molecular conductor consisting of a borazine ring sandwiched between two Au(100) electrodes with a finite cross section. The projected density of states (PDOS) and transmission coefficients under various external voltage biases are analyzed, and it suggests that the variation of the coupling between the molecule and the electrodes with external bias leads to NDR. Therefore, we propose that one origin of NDR in molecular devices is caused by the characteristics of both the molecule and the electrodes as well as their cooperation, not necessarily only by the inherent properties of certain species of molecules themselves. The changes of charge state of the molecule have minor effects on NDR in this device because the Mulliken population analysis shows that electron occupation variation on the molecule is very small when different external biases are applied.
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences and Graduate School of the Chinese Academy of Sciences, Hefei 230031, P.R. China.
authors.forename: Xingqiang
authors.initials: X
authors.lastname: Shi
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zheng
authors.forename: Zhenxiang
authors.initials: Z
authors.lastname: Dai
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zeng