We investigate the electronic transport properties of dihydroazulene(DHA) and vinylheptafulvene(VHF) molecule sandwiched between two carbon nanotubes using density functional theory and non-equilibrium Greeńs function. The device displays significantly switching behavior between DHA and VHF isomerization. It is found the different substitution position of F in the molecule influences the switching ratio of device, which is analyzed by transmission spectra and molecular projected self-consistent Hamiltonian. The observed negative differential resistance effect is explained by transmission spectra and transmission eigenstates of transmission peak in the bias window. The observed reverse of current in VHF form in which two H atoms on the right side of the benzene ring of the molecule are replaced by F is explained by transmission spectra and molecule-electrode coupling with the varied bias. The results suggest that the reasonable substitution position of molecule may improve the switching ratio, displaying a potential application in future molecular circuit.

我们使用密度泛函理论和非平衡Greeńs函数研究了夹在两个碳纳米管之间的二氢azulene（DHA）和乙烯基七氟丁烯（VHF）分子的电子传输性质。该设备在DHA和VHF异构化之间显示出明显的切换行为。发现分子中F的不同取代位置会影响器件的切换率，并通过透射光谱和分子投影自洽哈密顿量进行了分析。观察到的负微分电阻效应由偏置窗口中的透射光谱和透射峰的透射本征态解释。观察到的VHF形式的电流反向，其中分子的苯环右侧的两个H原子被F取代，这是通过透射光谱和分子电极与变化的偏压耦合来解释的。结果表明，合理的分子取代位置可以提高开关比例，在未来的分子电路中显示出潜在的应用前景。