Hernández-Rojas J, Bretón J, Gomez Llorente J M, Wales D J
Departamento de Física Fundamental II, Universidad de La Laguna, 38205 Tenerife, Spain.
J Phys Chem B. 2006 Jul 13;110(27):13357-62. doi: 10.1021/jp0572582.
Likely candidates for the global potential energy minima of C60(H2O)n clusters with n < or = 21 are found using basin-hopping global optimization. The potential energy surfaces are constructed using the TIP4P intermolecular potential for the water molecules, a Lennard-Jones water-fullerene potential, and a water-fullerene polarization potential, which depends on the first few nonvanishing C60 multipole polarizabilities. This combination produces a rather hydrophobic water-fullerene interaction. As a consequence, the water component of the lowest C60(H2O)n minima is quite closely related to low-lying minima of the corresponding TIP4P (H2O)n clusters. In most cases, the geometrical substructure of the water molecules in the C60(H2O)n global minimum coincides with that of the corresponding free water cluster. Exceptions occur when the interaction with C60 induces a change in geometry. This qualitative picture does not change significantly if we use the TIP3P model for the water-water interaction. Structures such as C60@(H2O)60, in which the water molecules surround the C60 fullerene, correspond to local minima with much higher potential energies. For such a structure to become the global minimum, the magnitude of the water-fullerene interaction must be increased to an unphysical value.
使用盆地跳跃全局优化方法找到了n≤21的C60(H2O)n团簇全局势能极小值的可能候选结构。势能面是利用水分子的TIP4P分子间势、Lennard-Jones水-富勒烯势以及水-富勒烯极化势构建的，该极化势取决于C60的前几个非零多极极化率。这种组合产生了相当疏水的水-富勒烯相互作用。因此，最低的C60(H2O)n极小值中的水成分与相应的TIP4P (H2O)n团簇的低势能极小值密切相关。在大多数情况下，C60(H2O)n全局极小值中水分子的几何子结构与相应的自由水团簇的几何子结构一致。当与C60的相互作用引起几何结构变化时会出现例外情况。如果我们使用TIP3P模型来描述水-水相互作用，这种定性描述不会有显著变化。诸如C60@(H2O)60这样的结构，其中水分子围绕着C60富勒烯，对应于势能高得多的局部极小值。要使这样的结构成为全局极小值，水-富勒烯相互作用的强度必须增加到不现实的值。
