用耦合簇理论及相关一致五重基研究H_2S(C_(2v),X^1A′)的解析势函数  

Investigation on analytic potential energy function of H_2S(C_(2v),X^1A′) using CCSD(T) theory combining with quintuple correlation-consistent basis set

作　　者：张金平[1] 刘慧[1] 施德恒[1] 孙金锋[2] 

机构地区：[1]信阳师范学院物理电子工程学院,信阳464000 [2]河南师范大学物理系,新乡453007

出　　处：《原子与分子物理学报》2009年第3期394-400,共7页Journal of Atomic and Molecular Physics

基　　金：河南省高校科技创新人才支持计划(2008HASTIT008);国家自然科学基金(10574039;10874064);河南省科技厅基础研究项目(082300410050)

摘　　要：运用CCSD(T)理论和相关一致五重基对基态H_2S分子进行了结构优化以及离解能和频率的计算,得到的结果是:该分子的基态为C_(2v)结构,平衡核间距R_(S-H)=0.13374nm,键角∠HSH=92.3837°,离解能D_0(H-SH)=3.8999 eV,频率v_1(a_1)=1121.1865 cm^(-1),v_2(a_1)=2727.5121 cm^(-1),v_3(a_1)=2742.8342 cm^(-1).这些结果与实验结果均较为相符.对H_2(X^1∑_g^+)分子使用cc-pV6Z、对SH(X^2Ⅱ)自由基使用aug-cc-pV5Z基组进行几何优化和谐振频率的计算并进行单点能扫描,且将单点能扫描结果拟合成了解析的Murrell-Sorbie函数.与实验结果及其它理论结果的比较表明,本文关于SH(X^2Ⅱ)自由基光谱常数(D_e,R_e,ω_e,B_e,α_e和ω_eX_e)的计算结果达到了较高的精度.采用多体项展式理论导出了H_2S(C_(2v),X^1A′)分子的解析势能函数,其等值势能图准确再现了该分子的离解能和平衡结构特征.报导了H_2S(C_(2v),X^1A′)分子对称伸缩振动等值势能图中存在的两个对称鞍点,对应于反应SH+H→SH_2,势垒高度为0.1680×4.184kJ/mol.The CCSD(T) theory in combination with the quintuple correlation-consistent basis set is used to determine the equilibrium geometry, dissociation energy and vibrational frequencies of the groundstate H_2S molecule. The values obtained at cc-pV5Z are of 0. 13374 nm for the equilibrium bond length R_(s-H), 92. 3837° for the bond angle ∠HSH,3. 8999 eV for the bond dissociation energy D_o (H-SH) and 1121. 1865 cm^(-1), 2727. 5121 cm^(-1) and 2742. 8342 cm^(-1) for the vibrational frequencies v_l (a_1),v_2 (a_1) and v_3 (a_1), respectively. These results have been found to be in excellent agreement with the available experiments. The equilibrium geometry, vibrational frequency and potential energy curve of the SH(X^2 Π) radical are calculated at the CCSD(T)/aug-cc-pV5Z level of theory. The ab initio points are fitted to the Murrell-Sorbie function with the least-squares method. The spectroscopic parameters, whether they are directly determined by the Gaussian 03 program package or they are derived from the analytic potential energy function (APEF), conform almost perfectly with the available experiments. The H_2 S (C_(2v), X^1 A’) APEF is derived by using the many-body expansion theory. Corresponding to the reaction SH + H→ SH_2,tWO symmetrical saddle points have been found at (0. 280 nm, 0. 144 nm) and (0. 144 nm, 0. 280 nm), respectively. And the barrier height is equal to 0. 1680 × 4. 184 kJ/mol.

关 键 词：H2S MURRELL-SORBIE函数 多体项展式理论 解析势能函数 

分 类 号：O561.1[理学—原子与分子物理]