摘要
用含时密度泛函理论(TDDFT)和差分密度泛函理论(△SCF-DFT)研究了氯代二苯并二恶英(PCDDs)的紫外可见电子吸收光谱。通过对分子轨道组成成份的详细分析以及电子跃迁过程的模拟,对吸收光谱中的每个峰进行了归属。同时研究了氯取代基对PCDDs吸收光谱的影响,发现随着氯取代基数目的增加,在低能区激发能几乎没有变化,而在较高能区激发能迅速降低,这与TCDD光谱图中第一个峰是氧和碳环之间的电子跃迁相一致。这说明与氯取代基相关的跃迁位于高能区,故用光降解方法试图减少氯取代基数目以降低PCDDs的毒性是不可能有效的。
A detailed analysis of UV-V is electronic absorption spectra for the polychlorinated dibenzo-p-dioxins（PCDDs） congeners have been reported by time-dependent density functional theory （TDDFT） and self-consistent-field density functional theory （ASCFDFT） methods. Through the analysis on the composition of orbital and the simulation of the electronic excitations, we have assigned every excitation peaks. We found that with the amounts of chlorine atom in the molecule increasing, there are nearly no influence on the excitation energies of the foremost three lowest-lying excitations, but the excitation energies are decreased in the following higher-lying excitations. It is consistent with our assignments that the first peak was mainly the excitations between oxygen and carbon rings. It shows that the excitations relating to the chlorine substitucnts were appeared at relatively higher energy regions. Therefore, it is not effective to attempt to decrease the amounts of chlorine substituents by the method of photo-degradation to reduce the toxicity of PCDDs.
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2006年第6期554-558,共5页
Computers and Applied Chemistry
关键词
氯代二苯并二嗯英
电子吸收光谱
电子跃迁
含时密度泛函理论
polychlorinated dibenzo-p-dioxins （PCDDs） , electronic absorption spectra, electronic exitations, the time-dependent density functional theory
