Structures of water octamers (H2O)8:: Exploration on ab initio potential energy surfaces by the scaled hypersphere search method
Structures of water octamers (H2O)8:: Exploration on ab initio potential energy surfaces by the scaled hypersphere search method
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DOI：
10.1021/jp070606a
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发表时间：
2007-05-24
影响因子：
2.9
通讯作者：
Ohno, Koichi
中科院分区：
文献类型：
--
作者：
Maeda, Satoshi;Ohno, Koichi
通过缩放超球面搜索方法探索了水八聚体的势能面（PES）。 PES上的164个极小值（基于MP2/6-311++G(3df,2p)//B3LYP/6-311+G(d,p)计算）中，具有D-2d对称性的立方结构已被确认为全局极小值。在使用这 164 种结构的热力学模拟中，具有 S-4 对称性的立方结构在低温下具有最高的布居数，尽管随着温度升高，双环可能变得占主导地位，这与最近使用经验势的蒙特卡罗模拟非常一致。当模拟中采用B3LYP/6-311+G(d,p)计算的势能数据时，从立方到非立方的转变温度被显着低估。 MP2 和 B3LYP 结果之间的这种严重差异表明分散相互作用对于讨论水八聚体热力学的重要性。
The potential energy surface (PES) of water octamers has been explored by the scaled hypersphere search method. Among 164 minima on the PES (based on MP2/6-311++G(3df,2p)//B3LYP/6-311+G(d,p) calculations), the cubic structure with D-2d symmetry has been confirmed to be the global minimum. In a thermodynamic simulation using these 164 structures, the cubic structure with S-4 symmetry has the highest population at low temperature, though double rings can become dominant as temperature going up, in good accord with a recent Monte Carlo simulation using an empirical potential. A transition temperature from cubic to noncubic has significantly been underestimated when potential energy data of B3LYP/6-311+G(d,p) calculations are employed in the simulation. This serious discrepancy between the MP2 and the B3LYP results suggests an importance of dispersion interactions for discussions on thermodynamics of water octamers.