Department of Chemistry, University of California, Davis, California 95616, USA.
J Phys Chem A. 2010 Feb 4;114(4):1944-52. doi: 10.1021/jp9095425.
We investigated intermolecular interactions in weakly bonded molecular assemblies from first principles, by combining exact exchange energies (EXX) with correlation energies defined by the adiabatic connection fluctuation-dissipation theorem, within the random phase approximation (RPA). We considered three different types of molecular systems: the benzene crystal, the methane crystal, and self-assembled monolayers of phenylenediisocyanide, which involve aromatic rings, sp(3)-hybridized C-H bonds, and isocyanide triple bonds, respectively. We describe in detail how computed equilibrium lattice constants and cohesive energies may be affected by the input ground state wave functions and orbital energies, by the geometries of molecular monomers in the assemblies, and by the inclusion of zero-point energy contribution to the total energy. We find that the EXX/RPA perturbative approach provides an overall satisfactory, first-principles description of dispersion forces. However, binding energies tend to be underestimated, and possible reasons for this discrepancy are discussed.
我们通过在随机相位近似（RPA）中结合精确交换能（EXX）和由绝热连接涨落耗散定理定义的相关能量，从第一性原理研究了弱键合分子组装体中的分子间相互作用。我们考虑了三种不同类型的分子体系：苯晶体、甲烷晶体和苯二异氰酸酯的自组装单层，分别涉及芳环、sp(3)杂化的 C-H 键和异氰酸酯三键。我们详细描述了计算得到的平衡晶格常数和内聚能如何受到输入基态波函数和轨道能、组装体中分子单体的几何形状以及总能量中零点能贡献的影响。我们发现，EXX/RPA 微扰方法为色散力提供了一种整体令人满意的第一性原理描述。然而，结合能往往被低估，并且讨论了这种差异的可能原因。
