Theoretical prediction of low-lying structures of [CH3NH3NO3]n(n = 1–20) protic ionic liquid clusters
作者单位：College of Chemistry and Chemical EngineeringJiangxi Normal University
会议名称：《中国化学会第十二届全国量子化学会议》
会议日期：2014年
学科分类：081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学]
基 金：supported by the Natural Science Foundation of China(No.21306070)
摘 要：The low-lying structures of[CH3NH3NO3]n protic ionic liquid clusters up to 20 ion-pairs have been explored by the combination of empirical OPLS-AA force field and high-level M06-2X ***,a series of independent molecular dynamics(MD)simulations with the empirical force field are carried out at different temperatures to produce at least 105 conformations for n***,these MD conformations are optimized through a low-storage nonlinear optimization method to create a large database of local minima structures at the level of empirical force ***,single-point energy calculations at M06-2X/6-31G(d)are performed for the lowest 500 local ***,the lowest 10 structures obtained from the M06-2X/6-31G(d)energies are as starting points for full geometry optimizations at the same *** calculations demonstrate clearly that the low-lying structures of[CH3NH3NO3]n clusters begin to form the cubic cage structure at n=*** the cluster size increases up to n=7,10,and 13,one-,two-,and three-centered cage structures can be formed with the interior anions(NO3–),***,a four-centered cage structure embedded with one cation and three anions is found at n=16 while three five-centered cage structures embedded with one cation and four anions are found at n≥*** analysis,we find that the anions prefer to locate in the inner region compared to the cations owing to the smaller size and lower surface energy of ***,these cage structures mainly consist of four-and six-membered rings through the hydrogen-bond(HB)network between cations and anions and few odd-membered rings can be found for all low-lying *** addition,the relevant HBs and relative stabilities of[CH3NH3NO3]n clusters are also discussed in detail.