CAJ | 학술논문

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Si5H4的所有结构进行了计算研究，结果发现 Si5H4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。
선용3충불동적밀도범함이론방법（B3LYP，BHLYP，BPW91），재전전자적쌍ζ가겁화가미산기조(DZP++)하，대Si5H4적소유결구진행료계산연구，결과발현 Si5H4가능존재2충기태결구。대차，위료획득경정학적계산결과，아문재MP3/6-311++G(d,p)+ZPE적이론급별상，대저2충구형이급정개반응과정중적과도태、중간체적이구화반응진행료동역학연구，병차대과도태적진동모식이급각주점적정전하진행분석，학인료TS1화TS2적합이성，이차표명반응I위정개반응적공제보취。
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 ΔGθ298 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.