外场下SiSe分子结构及激发特性研究  

Study on the Structure and Properties of SiSe Molecule under the External Electric Field

作　　者：吴学科[1] 黄意[2] 唐延林[3] WU Xue-ke;HUANG Yi;TANGD Yan-lin(Kaili University,Kaili,Guizhou,556011,China;Guizhou University,Guiyang,Guizhou,550025,China)

机构地区：[1]凯里学院理学院,贵州凯里556011 [2]凯里学院,贵州凯里556011 [3]贵州大学,贵州贵阳550025

出　　处：《凯里学院学报》2019年第6期18-22,共5页Journal of Kaili University

基　　金：凯里学院博士专项课题资助(BS201802)

摘　　要：采用局域自旋密度近似(LSDA)方法,在311++g(3df,3pd)基组水平上对不同外电场下SiSe分子的几何结构进行优化,并分析分子电偶极矩、总能量、HOMO能级、LUMO能级和能隙等随外场的变化情况,然后采用杂化CIS方法计算外电场下SiSe分子的激发特性及电子光谱,结果表明:在外电场作用下,分子键长、总能量、偶极矩和紫外-可见光谱等受到明显影响;外电场由-0.04a.u.到0.04a.u.变化过程,键长和偶极矩先减小后增大,而总能量则先增大后减小,当电场F=0.01a.u.时总能量达到最大值,偶极矩达到最小值;当外电场在-0.020~0.020a.u.范围变化时,能隙E G受影响较小,当外加电场由-0.020变化到-0.040a.u.和0.020变化到0.040a.u.时,能隙E G急剧下降;当外加电场较小时分子电子光谱对应紫外发光,当施加负向外电场F=-0.040a.u.时,在可见光区域476.6nm处出现较强吸收峰.Local spin density approximation(LSDA)method was used to optimize the geometrical structure of SiSe molecule under different external electric fields at 311++G(3df,3pd)basis set level.The variation of molecular dipole moment,total energy,HOMO energy level,LUMO energy level and energy gap with the external field was analyzed.Then the excitation characteristic and electronic spectrum of SiSe molecule was calculated by CIS method.The results show that the bond length,total energy,dipole moment and ultraviolet-visible spectra of the molecule are obviously affected by the external electric field,and the bond length and dipole moment decrease first and then increase,while the total energy increases first and then decreases with the change of the external electric field from-0.04a.u.to 0.04a.u.When the electric field F=0.01 a.u.,the total energy reaches the maximum and the dipole moment reaches the minimum value.When the external electric field change from-0.020 to 0.020 a.u.,the gap E G is less affected,while the external electric field change from 0.020 to 0.040 a.u.and from-0.020 to-0.040a.u.,the gap E G decreases sharply.The electron spectra correspond to ultraviolet luminescence when the external electric field is small.The electron spectra correspond to ultraviolet luminescence when the external electric field is small,then a strong absorption peak appears at 476.6nm in the visible region when negative external electric field F=-0.040 a.u.is applied.

关 键 词：SiSe 外电场 激发态 紫外-可见光谱 

分 类 号：P22[天文地球—大地测量学与测量工程]