Convergence of the Many-Body Expansion for Energy and Forces for Classical Polarizable Models in the Condensed Phase
Convergence of the Many-Body Expansion for Energy and Forces for Classical Polarizable Models in the Condensed Phase
复制标题
DOI：
10.1021/acs.jctc.6b00335
复制
发表时间：
2016-08-01
影响因子：
5.5
通讯作者：
Head-Gordon, Teresa
中科院分区：
文献类型：
--
作者：
Demerdash, Omar;Head-Gordon, Teresa
我们分析的AMOEBA经典的极化模型的能量和力量的收敛时，作为一个多体膨胀（MBE）对相应的N-体母势的凝聚相水模拟的背景下进行评估。这与大多数基于量子力学的分子束外延公式相反，后者只关注气相团簇的能量收敛。使用一个单一的水分子作为一个机构的定义，我们发现，截断的MBE在第三阶，3 AMOEBA，捕捉直接极化准确，并产生明显的良好的相互极化能量的收敛。然而，它呈现在极化力的大小的大的误差，并需要至少四阶项的MBE向父电位梯度值收敛。我们可以通过将二聚体和三聚体的极化响应嵌入到整个系统的固定静电的完整表示中来改善3-AMOEBA的极化力的收敛。我们表明，静电嵌入形式主义有助于确定具体的配置，涉及线性氢键的安排，在3体水平收敛性差。通过将一个物体的定义扩展为一个大的水簇，我们可以减少力的误差，产生一个近似的极化模型，比母势快10倍。3-AMOEBA模型提供了新的方法来研究本体水的性质如何取决于液体中的连接程度。
We analyze convergence of energies and forces for the AMOEBA classical polarizable model when evaluated as a many-body expansion (MBE) against the corresponding N-body parent potential in the context of a condensed-phase water simulation. This is in contrast to most MBE formulations based on quantum mechanics, which focus only on convergence of energies for gas-phase clusters. Using a single water molecule as a definition of a body, we find that truncation of the MBE at third order, 3 AMOEBA, captures direct polarization exactly and yields apparent good convergence of the mutual polarization energy. However, it renders large errors in the magnitude of polarization forces and requires at least fourth-order terms in the MBE to converge toward the parent potential gradient values. We can improve the convergence of polarization forces for 3-AMOEBA by embedding the polarization response of dimers and trimers within a complete representation of the fixed electrostatics of the entire system. We show that the electrostatic embedding formalism helps identify the specific configurations involving linear hydrogen-bonding arrangements that are poorly convergent at the 3 body level. By extending the definition of a body to be a large water cluster, we can reduce errors in forces to yield an approximate polarization model that is up to 10 times faster than the parent potential. The 3-AMOEBA model offers new ways to investigate how the properties of bulk water depend on the degree of connectivity in the liquid.