采用密度泛函理论方法系统地研究了由不同结构转变方式引发的一系列光致变色分子在用于分子开关时的电子输运性质. 对各种分子结构转变前后的最高占据轨道(HOMO)与最低空轨道(LUMO)的能级间隙(HLG)、前线轨道的空间分布、电子透射谱和投影电子态密度(PDOS)谱进行了计算和讨论. 结果表明，相似的结构转变方式通常造成分子具有相似的电流开关性质，这与分子的共轭程度又有一定的关系. 比较各种分子的电流开关比后发现偶氮苯结构单元具有最大的电流开关比.A series of model molecules with 4 kinds of conformational transformations have been investigated as optical molecular switches by using density functional theory combined with nonequilibrium Green’s function method. The theoretical calculations show that molecules after conformational transformations have photoswitching characteristics. We find that the photochromic molecules with the same conformational transformation usually have a similar current on/off state when they are applied as photoshwitches. Among these transformations, the molecular switch with E(“trans”)/Z(“cis”)-isomerisation of the NN double bond has the highest current on-off ratio. The influences of the energy gap (HLG) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), spatial distributions, transmission and projected density of states (PDOS) spectra on the electronic transport through the optical molecular switches are discussed in detail.This work was supported by National Natural Science Foundation of China (Nos. 51071084, 21273113, 21121091 and 11204120) and National Key Technology R&D Program of China (No. 2012BAF03B05)This work was supported by National Natural Science Foundation of China (Nos. 51071084, 21273113, 21121091 and 11204120) and National Key Technology R&D Program of China (No. 2012BAF03B05)作者联系地址：南京大学 化学化工学院，生命分析化学国家重点实验室，江苏 南京 210008Author's Address: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210008, China通讯作者E-mail：[email protected]
