氟代乙烯阳离子的理论研究

用B3LYP和MP2方法及6-31G(d, p)、6-31＋G(d, p)、6-311G(d, p)和6-311＋G(d, p) 基组，对六种氟代乙烯阳离子做了理论研究，优化了它们的基电子态的结构，计算了对应分子的垂直电离势（VIP）和绝热电离势(AIP).结果表明，与具有非平面结构的乙烯阳离子不同，六种氟代乙烯阳离子都只具有平面结构；与分子结构相比，离子结构的C－C键增长， C－F键缩短， CCF键角变小. 自然布居分析计算表明，这些离子的正电荷主要分布在与F原子相连的C原子和各H原子上. B3LYP/6-311＋G(d, p) 级别上计算的各分子的VIP和AIP值和实验值符合得很好. 使用含弥散基函数的基集可以明显提高这类分子的电离势的计算精度.

Theoretical Study on Fluorinated Ethylene Cations

Cations of C2H3F ,, cis CHF=CHF , trans CHF=CHF , , and were studied by using the DFT B3LYP and ab into MP2 methods in conjunction with the 6 31G(d,p), 6 31 G(d,p), 6 311G(d,p), and 6 311 G(d,p)basis sets. Geometry optimization calculations indicate that all the six fluorinated ethylene cations have planar structures, in contrast with the non planar D2 structure of the ethylene cation. Differences in geometry between the cations and their parent molecules were examined. Natural population analysis calculations indicate that the positive charge resides mainly at the C atom connecting with the F atom and at the H atoms in these cations. The B3LYP calculations with the 6 311 G(d,p) basis predict vertical and adiabatic ionization potential(VIP and AIP) values of the fluorinated ethylene molecules in good agreement with the experimental values. Diffuse basis functions in the basis sets are important for accurate prediction of the VIPs and AIPs for the fluorinated ethylene molecules.