IQTCUB, Departament de Química Física, Universitat de Barcelona, Barcelona, Spain.
Phys Chem Chem Phys. 2011 May 14;13(18):8422-32. doi: 10.1039/c0cp01763a. Epub 2011 Feb 18.
A recently formulated intermolecular potential has been adapted to describe the interaction of the N-methylacetamide (NMA) dimer and of the NMA-H(2)O adduct. The pure electrostatic component of the intermolecular potential functional representation is as usual expressed in terms of a set of punctual charges distributed over the molecular frames, consistently with the permanent molecular dipole values. In contrast, the remainder of the intermolecular potential is expressed in terms of Improved Lennard Jones effective pair potential functions, referred to multiple interaction centers (or sites) placed on the N-methylacetamide molecule and to a single interaction center placed on the water molecule. The characteristic of this pair potential relies on a mix of transferable and non-transferable descriptions of the parameters. The first set of parameters has a structural connotation bearing a site-site interaction nature and exploiting the molecular polarizability decomposability. The second one, depending on the particles clustering and charge distribution and transfer, bears a delocalized and ambient bulk nature. This choice has been tested against ab initio calculations and molecular dynamics simulations. The results show that the model potential is appropriate for describing the energetic of the various stable configurations of NMA-NMA and NMA-H(2)O weakly interacting aggregates, including the formation of hydrogen bonds.
最近提出的一种分子间相互作用势能已被用于描述 N-甲基乙酰胺（NMA）二聚体和 NMA-H2O 加合物的相互作用。分子间势能函数表示的纯静电分量通常采用一组分布在分子骨架上的点电荷来表示，与永久分子偶极矩值一致。相比之下，分子间势能的其余部分采用改进的 Lennard-Jones 有效对势能函数来表示，涉及放置在 N-甲基乙酰胺分子上的多个相互作用中心（或位点）和放置在水分子上的单个相互作用中心。这种对势能的特点在于参数的可传递和不可传递描述的混合。第一组参数具有结构内涵，具有位点间相互作用性质，并利用分子极化率可分解性。第二组参数取决于粒子聚类和电荷分布以及转移，具有离域和环境整体性质。已经针对从头计算和分子动力学模拟对该模型势能进行了测试。结果表明，该模型势能适用于描述 NMA-NMA 和 NMA-H2O 弱相互作用聚集体的各种稳定构型的能量，包括氢键的形成。
