论文部分内容阅读
采用密度泛函理论B3LYP方法研究了SiF2自由基与异硫氰酸(HNCS)的反应机理,并在B3LYP/6-311++G**水平上对反应物、中间体、过渡态进行了全几何参数优化,通过频率分析和内禀反应坐标(IRC)确定中间体和过渡态的真实性.为了得到更精确的能量值,又用CCSD(T)/6-311++G**方法计算了在B3LYP/6-311++G**水平优化后的各个驻点的相对能量.根据统计热力学及用Winger校正的Eyring过渡态理论,利用自编程序,计算不同温度下低势垒反应的平衡常数和速率常数,并且通过电子密度拓扑分析讨论了化学反应过程中主要化学键的生成和断裂.计算结果表明,单重态的SiF2自由基与HNCS反应有6条可能的反应通道,其中反应通道SiF2+HNCS→IM1→TS1→IM2HSiF2NCS(P1)为主反应通道.
The reaction mechanism of SiF2 radical with isothiocyanic acid (HNCS) was studied by using density functional theory (B3LYP) method and the reactants, intermediates and transition states were all carried out at B3LYP / 6-311 ++ G ** level Geometric parameters are optimized to determine the authenticity of intermediates and transition states by frequency analysis and intrinsic reaction coordinates (IRC). To obtain more accurate energy values, CCSD (T) / 6-311 ++ G ** method is also used to calculate Based on the statistical thermodynamics and the Eyring transition state theory with Winger’s correction, a self-programmed program is used to calculate the relative energy of each potential point at B3LYP / 6-311 ++ G ** level. Equilibrium constants and rate constants, and the formation and cleavage of the major chemical bonds during the chemical reaction are discussed by electron density topological analysis. The calculated results show that there are six possible reaction channels for the reaction of singlet SiF2 with HNCS. The reaction channels SiF2 + HNCS → IM1 → TS1 → IM2HSiF2NCS (P1) as the main reaction channel.