Li Jianfu, Zhang Rui-Qin
Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, China.
Sci Rep. 2016 Mar 1;6:22304. doi: 10.1038/srep22304.
For the first time, the intermolecular orbital interaction between benzene and methane in the benzene-methane complex, a representative of weak interaction system, has been studied by us using ab initio calculations based on different methods and basis sets. Our results demonstrate obvious intermolecular orbital interaction between benzene and methane involving orbital overlaps including both occupied and unoccupied orbitals. Similar to interatomic orbital interaction, the intermolecular interaction of orbitals forms "bonding" and "antibonding" orbitals. In the interaction between occupied orbitals, the total energy of the complex increases because of the occupation of the antibonding orbital. The existence of the CH-π hydrogen bond between benzene and methane causes a decrease in rest energy level, leading to at least -1.51 kcal/mol intermolecular interaction energy. Our finding extends the concept of orbital interaction from the intramolecular to the intermolecular regime and gives a reliable explanation of the deep orbital reformation in the benzene-methane complex.
我们首次采用基于不同方法和基组的从头算方法，对苯 - 甲烷复合物（一种弱相互作用体系的代表）中苯和甲烷之间的分子间轨道相互作用进行了研究。我们的结果表明，苯和甲烷之间存在明显的分子间轨道相互作用，涉及包括占据轨道和未占据轨道在内的轨道重叠。与原子间轨道相互作用类似，轨道的分子间相互作用形成了“成键”和“反键”轨道。在占据轨道之间的相互作用中，由于反键轨道的占据，复合物的总能量增加。苯和甲烷之间CH - π氢键的存在导致剩余能级降低，产生至少 -1.51 kcal/mol的分子间相互作用能。我们的发现将轨道相互作用的概念从分子内扩展到了分子间领域，并对苯 - 甲烷复合物中深刻的轨道重整给出了可靠的解释。
