中文摘要：

采用密度泛函理论B3LYP方法在6-31G（d，P）水平对一类推／拉型螺烯分子进行了几何结构优化，在得到稳定的分子构型后，用ZINDO／SCI方法计算了它们的前线分子轨道和电子光谱．结果表明，不同取代基和取代基的不同位置对分子的空间几何构型有一定的影响，HOMOs和LUMOs的分布特点说明该类分子有明显的电荷转移特征，通过优化设计不但可以提高非线性光学系数还可以增强这类分子的透明性．

英文摘要：

The geometries of a series of push-pull helicenes were optimized by using density functional theory B3LYP method at the 6-31（; （d, p） basis set level. Based on the obtained stable molecular configuration; the frontier molecular orbits and electronic spectras of these molecules were calculated by using the ZINDO/SCI method. The re- sults showed that the spatial molecular structures were different when the substituents or their positions were different. Through optimizing design, the distributions of HOMOs and LUMOs showed that these molecules have obviously charge transfer properties. Not only the nonlinear coefficients of this series of helicenes can be increased, but also the transpar- ences of such molecules call be enhanced.