Pires Marcos M, DeTuri Vincent F
Department of Chemistry, Ithaca College, Ithaca, New York 14850.
J Chem Theory Comput. 2007 May;3(3):1073-82. doi: 10.1021/ct600348x.
An investigation of gas-phase methanol clusters (CH3OH)n, where n = 2-12, 16, and 20, was completed with a range of computational methods: PM3, Hartree-Fock, B3LYP, MP2, and their combination using an ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) method. Geometries, binding energies, and vibrational frequencies are reported. For all ab initio optimized structures, the cyclic isomer was found to be the most stable structure of all isomers investigated. The scaled OH frequency shift for n = 1-4 is found to be in good agreement with experimentally measured shifts. An ONIOM method, with the methyl group calculated at the low level and the hydroxyl group at the high level, proved to be an excellent way of reducing computational expense. The calculated enthalpies, geometries, and infrared spectra using an ONIOM method were comparable to that of a high-level calculation. Clusters were solvated using the integral equation formalism for the polarized continuum model method to compare with the microsolvation studies.
利用一系列计算方法对气相甲醇团簇(CH₃OH)ₙ（其中n = 2 - 12、16和20）进行了研究：PM3、哈特里 - 福克方法、B3LYP、MP2以及使用我们自己的n层集成分子轨道和分子力学（ONIOM）方法将它们进行组合。报告了几何结构、结合能和振动频率。对于所有从头算优化结构，发现环状异构体是所研究的所有异构体中最稳定的结构。发现n = 1 - 4时缩放后的OH频移与实验测量的频移吻合良好。一种ONIOM方法，即甲基在低水平计算而羟基在高水平计算，被证明是降低计算成本的极佳方法。使用ONIOM方法计算的焓、几何结构和红外光谱与高水平计算结果相当。使用积分方程形式的极化连续介质模型方法对团簇进行溶剂化处理，以与微溶剂化研究进行比较。
