中文摘要：

采用密度泛函理论方法，在B3LYP／6-31G（d，P）水平上研究氯化胆碱离子对的几何与电子结构。共有四种稳定离子对构型被发现。在稳定离子对结构中，Cl^-离子倾向与阳离子形成多重稳定氢键。阴阳离子间的氢键相互作用主要通过Cl^-离子的LPCl轨道和阳离子的σC-H^＊，或σO-H^＊轨道间的相互作用完成。研究发现这种盯相互作用很弱，由此判断阴阳离子间大的相互作用能并不是单纯的氢键作用能，还包含阴阳离子间静电作用能的贡献；而且是主要贡献。阴阳离子间大的相互作用能还为氯化胆碱的高熔点提供了解释。

英文摘要：

The geometrical and electronic structures of choline chloride ion pair have been studied by perform- ing density functional theory calculations on the B3 LYP/6-31 G（ d, p） level. Four stable configurations for choline chloride ion pair have been obtained. It is found that there exist multiply hydrogen bonds between cation and Cl^- anion. The intrinsic hydrogen bond interaction between the cation and Cl^- anion mainly occurs between one LPCl of Cl^- anion and the σC-H^＊ or σO-H^＊ orbitals of the cation moiety. However, the σ-type interactions are weak. Therefore, it is considered that ion pair is highly stable owing to not only the multiple hydrogen bond interactions, but also the strong electrostatic attraction. The large interaction energy between the cation and Cl^- anion may he responsible for the higher melting point of choline chloride.