The organophosphate pesticides, parathion and methyl-parathion, are studied in this paper. Their ground-state configurations are optimized by the AMI semi-empirical method of the quantum chemistry. Then, the ground-state configurations are optimized to the excited states configurations by the method of single excited interactions CIS. On this basis, the absorption spectra of their ground-state configurations and the fluorescence spectra of their excited-state are computed on the level of B3LYP/6-31 +G(d) .using the time dependent density functional theory (TD-DTF). The imaginary frequency does not appear from the vibration analysis of the optimized ground-state configurations. The computed spectra are compared with the spectra from that of the experiments using the English Edinburgh FLS920P spectrometer. The results show that they are coincided and the optimizations above are reasonable. This study provides theoretical support on the pesticide detection.%以常见的有机磷农药对硫磷和甲基对硫磷为对象,采用量子化学半经验方法AM1优化它们的基态构型,然后采用单激发组态相互作用CIS方法将基态构型优化为激发态构型.在此基础上,采用含时密度泛函TD-DTF,在B3LYP/6-31+ G(d)水平下,分别计算了它们基态构型的吸收光谱和激发态构型的荧光发射光谱.优化完成后的基态构型经振动分析,均未出现虚频率,说明得到的构型基本合理.比较优化完成后的基态和激发态的构型推测了光谱产生的机理,光谱的理论值与使用英国Edinburgh FLS920P光谱仪测得的实验值基本吻合,说明了推测的合理性.以上研究为农药的光谱检测提供了一定的理论支持.
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