中文摘要：

选用7种不同的密度泛函理论（DFT）方法：B3LYP,BLYP,BHLYP,BP86,B3P86,BPW91,B3PW91,采用全电子的双ζ加极化加弥散函数基组（DZP＋＋）,对SeHn/SeHn^-（n=1～5）的分子结构、电子亲合能和第一离解能进行了研究.结果表明,SeH/SeH^-,SeH2/SeH2^-,SeH3/SeH3^-,SeH4/SeH4^-和SeH5/SeH5^-的基态结构分别为C∝v/C∝v,C2v（^1A1）/Cs（^2A′）,Cs（^2A1）/C2v（^1A1）,C2v（^1A1）/C4v（^2A1）,C4v（^2A1）/C4v（^1A1）,其中,B3P86和B3PW91在预测分子结构方面比较好;在电子亲合能方面,BLYP方法预测是最可靠的;BP86方法预测的谐振频率与实验值接近;BHLYP能很好的预测第一离解能.

英文摘要：

Seven different density functional theory （DFT） methods were employed to predict the molecular structures, electron affinities, and first dissociation energies of the SeHn/SeHn^- （ n = 1-5 ） molecules. The three type of electron affinities reported in this work are the adiabatic electron affinity （ EAad ）, the vertical electron affinity （ EAvert）, and the vertical detachment energy （VDE）. The basis set used is of double-（ plus polarization quality with additional s- and p-type diffuse functions, labeled as DZP ＋ ＋. The ground states of Sell/SeH^-, SeH2/SeH2^-, SeH3/SeH3^-, SeH4/SeH4^- and SeH5/SeH5^- are C∝v/C∝v,C2v（^1A1）/Cs（^2A′）,Cs（^2A1）/C2v（^1A1）,C2v（^1A1）/C4v（^2A1）,C4v（^2A1）/C4v（^1A1）,respectively. Compared with the experimen tal values, the B3P86 and B3PW91 methods give good results for the molecular structures, the BLYP method in all of these schemes is the best in respect of predicting electron affinities, the BP86 method determines the vibrational frequencies in best agreement with experimental data, meanwhile, the BHLYP methods gives good results for the first dissociation energies.