O_2分子激发态b^1∑_g^+的势能函数

Potential energy function for the excited state b^1∑_g^+ of the molecule O_2

利用QCISD(T)、CISD、CID和HF方法在6-311+G*基组下对O2分子激发态b1∑g+的平衡结构和谐振频率进行了优化计算,对比所有计算结果,得出QCISD(T)为最优方法;利用QCISD(T)/6-311+G*方法对此态进行单点能扫描计算,用非线性最小二乘法拟合出了PG函数,得到了O2分子激发态b1∑g+的势能函数;分别将单点能扫描势能曲线与PG函数曲线和实验势能曲线进行对比,发现曲线符合得较好。

The equilibrium geometry and harmonic frequencies of the excited state b^1∑g^＋ of O2 molecule are calculated by using the methods of QCISD（T） ,CISD,CID and HF based on the set 6-311＋G^＊. The results by the above-mentioned four methods are compared, and it is concluded that the QCISD （T） method is most suitable for the energy calculation of the O2 molecule. The whole potential curve for the state is further scanned by using the QCISD（T）/6-311＋G^＊ method. The PG function is fitted by the least-squares method,and the potential function of the O2 molecule gained. By comparison with the scanned curve, the fitting curve and the experimental curve are found to be in good agreement.