The characterization of stationary points in the potential energy surface of difluoromethane dimer

详细信息    查看全文

• 作者：Ebrahimi ; Ali ; Roohi ; Hosein ; Mostafa Habibi ; Sayyed
• 关键词：Difluoromethane ; DFM ; Improper hydrogen bond ; NBO ; AIM
• 刊名：Journal of Molecular Structure: THEOCHEM
• 出版年：2004
• 出版时间：September 27, 2004
• 年：2004
• 卷：684
• 期：1-3
• 页码：87-93
• 全文大小：237 K

文摘

Various properties of the CHphs/BN9.GIF>FC interactions in difluoromethane (DFM) dimer were determined by HF, MP2, and B3LYP methods in 6-311++G(d,p) basis set. First, six different structures were proposed for (DFM)₂. It was found that some of these which are minimum structures in MP2 or HF methods are saddle structures in B3LYP method. The topological properties of electronic charge density were analyzed employing the Bader's Atoms in Molecules (AIM) theory. The results were successfully showed that all dimers exhibit a bond critical point (BCP) between each Hphs/BN9.GIF>F contact (with exceptions). In all cases, the values of ρ_BCP were obtained in the range of 0.005–0.008a.u., and the values of phs/CE1.GIF>p>2p> ρ_BCP were positive. Also, the wave function analysis was performed by Natural Bond Orbitals approach. The perturbation energy analyses were indicated that the donor–acceptor interactions within each unit are different from these interactions in the lone monomer. It seems that these changes are very important in decreasing of occupancies in σ*_CH orbitals, shortening of the C–H bonds, and blue shift of the C–H stretching frequencies.