使用SAC/SAC-CI方法,利用D95++* *、6-311++g* *以及cc-PVTZ等基组,对HD分子的基态(X^1∑_g^+)、第二激发态(B^1∑_u^+)和第三激发态(C^1Ⅱ_u)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了cc-PVTZ基组为三个基组中的最优基组的结论;使用cc-PVTZ基组,利用SAC的GSUM(Group Sum of Operators)方法对基态(X^1∑_g^+)、SAC-CI的GSUM方法对激发态(B^1∑_u^+)和(C^1Ⅱ_u)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X^1∑_g^+)、第二激发态(B^1∑_u^+)和第三激发态(C^1Ⅱ_u)相对应的光谱常数(B_e,α_e,ω_e和ω_eχ_e),结果与实验数据基本吻合.
Total internal partition sums are calculated in the product approximation at temperatures up to 6000 K for the asymptotic asymmetric-top SiO2 molecule.The rotational partition function and the vibrational partition function are calculated with the rigid-top model and in the harmonic oscillator approximation,respectively.Our values of the total internal partition sums are consistent with the calculated value in the Gaussian program within 0.137% at 296 K.Using the calculated partition functions and the rotationless transition dipole moment squared as a constant,we calculate the line intensities of 001-000 band of SiO2 at normal,medium and high temperatures.Simulated spectra of the 001-000 band of the asymptotic asymmetric-top SiO2 molecule at 2000,5000 and 6000 K are also obtained.
