摘要
选用3种不同的密度泛函理论方法(B3LYP,BHLYP,BPW91),在全电子的双ζ加极化加弥散基组(DZP++)下,对Si_5H_4的所有结构进行了计算研究,结果发现Si_5H_4可能存在2种基态结构。对此,为了获得更精确的计算结果,我们在MP3/6-311++G(d,p)+ZPE的理论级别上,对这2种构型以及整个反应过程中的过渡态、中间体的异构化反应进行了动力学研究,并且对过渡态的振动模式以及各驻点的净电荷进行分析,确认了TS1和TS2的合理性,而且表明反应I为整个反应的控制步骤。
Using three different density functional theory methods （B3LYP, BHLYP, BPW91）, and the double-ζplus polarization quality with additional s-and p-type diffuse functions（DZP＋＋）, has studied all the possible structures of Si5H4 on the potential energy surface （PES）. The result has shown that Si5H4 should have two low-lying structures, in which the B3LYP and BHLYP functionals predict that the A-type is lower in energy than the C-type by 0.09 and 0.31 eV, respectively, whereas the BPW91 functional predict that the C-type is more stable than the A-type structure by 0.09 eV. Indeed, in this case we cannot be sure which structure is more adjacent to the critical points, due to the flat potential energy surface of the SinHm clusters, and many isomeric arrangements are possible. Herein, accurate predictions of equilibrium geometries require advanced quantum mechanical investigations. For that, we has employed the higher accurate MP3/6-311＋＋G（d, p） theory level to compute the structures of reaction process, it is found that the local minimum is in Cs symmetry with ^1A＇ electronic state, and two transition states TS1 and TS2, and vibrational frequency analyses are carried out to confirm the stationary structure being a local minimum on the potential energy surface and the existence of transition states with respect to the corresponding produce directions. In the reactions, the results of energy barriers ΔE^≠, reaction energies ΔE and the changes on ΔG^θ 298 also indicate that the isomerization reaction I Si5H4（A） →Si5H4（B） has the 19.73 kJ/mol energy difference, whereas the reaction II Si5H4（B） → Si5H4（C） has the only 3.77 kJ/mol. Thus, the reaction I Si5H4（A） → Si5H4（B） should be the control step. In addition, the vibrational mode of the transition states and net charges of the stationary points are also explored for the detailed discussion in the work.
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2014年第9期1031-1034,共4页
Computers and Applied Chemistry
基金
陕西省教育厅基金(14JK2128)
西安市文理专项(CXY1352WL20)
陕西省自然科学基金(2014JM2046)
国家自然科学基金(11204239)
