采用量子化学从头算的HF,MP2,QCISD方法和密度泛函中的B3LYP方法,在不同基组6 311G(d) , 6 311G(2df) , 6 311G(3df) , 6 311++G(3df) 水平上对草酰碘中性分子(ICO)2 作了构像分析.结果表明,在不同基组水平上,由MP2,QCISD,B3LYP方法均能得到草酰碘分子的交叉式构型和平面反式构型,与实验所得草酰卤化物的构型完全相符. Using ab initio calculations of HF, MP2 and QCISD methods and B3LYP method in density functional theory, we have found that in the different basis sets of 6 311G (d), 6 311G (2df), 6 311G (3df), 6 311 ++ G ) Conformational analysis of oxalyl iodide neutral molecule (ICO) 2 was carried out.The results showed that the cross configuration of oxalyl iodide molecule could be obtained by MP2, QCISD and B3LYP methods at different basic level The trans configuration of the plane is in good agreement with the experimental configuration of the oxalyl halide.