在动量空间讨论二氯乙烯的同分异构性

Investigation of the isomerism of dichloroethylene in momentum space

通过量化计算得到了二氯乙烯偏式、顺式和反式三种同分异构体的几何结构参数,并利用电子动量谱学方法计算了二氯乙烯偏式、顺式和反式同分异构体的四个芯轨道的动量密度二维分布图和动量谱线.对比不同异构体的四个芯轨道在坐标空间和动量空间的电子分布情况发现,在坐标空间无法体现的原子轨道间的相互干涉作用在动量空间被放大了,表现为动量曲线具有多峰结构和一定的周期性.通过计算周期值可以求出不同异构体相邻原子间的间距;通过判断周期轴的方向能够得到三种异构体的分子轴取向.

The geometric parameters are optimized at the B3LYP and CI levels under the constraints of the C2v, C2v and C2v symmetry point groups for the three isomers of dichloroethylene. The theoretical two-dimensional electron momentum distributions and momentum profiles of four core orbitals for iso-dichloroethylene, cis-dichloroethylene and trans-dichloroethylene are calculated by non-relativistic density functional method. Comparing the electron distribu- tions in position and momentum space of these orbitals, it is found that the interference effects, which do not exit in position space, appear and produce the evident periodical multipeaked momentum distributions in momentum space. The distances between atoms and the alignments of molecular axes for these three isomers can be obtained by computing their values of period and the axis directions of period, respectively.