Heinemann Thomas, Palczynski Karol, Dzubiella Joachim, Klapp Sabine H L
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
Institut für Physik, Humboldt Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany.
J Chem Phys. 2015 Nov 7;143(17):174110. doi: 10.1063/1.4935063.
In this article, we present and compare two different, coarse-grained approaches to model electrostatic interactions of disc-shaped aromatic molecules, specifically coronene. Our study builds on our previous work [T. Heinemann et al., J. Chem. Phys. 141, 214110 (2014)], where we proposed, based on a systematic coarse-graining procedure starting from the atomistic level, an anisotropic effective (Gay-Berne-like) potential capable of describing van der Waals contributions to the interaction energy. To take into account electrostatics, we introduce, first, a linear quadrupole moment along the symmetry axis of the coronene disc. The second approach takes into account the fact that the partial charges within the molecules are distributed in a ring-like fashion. We then reparametrize the effective Gay-Berne-like potential such that it matches, at short distances, the ring-ring potential. To investigate the validity of these two approaches, we perform many-particle molecular dynamics simulations, focusing on the crystalline phase (karpatite) where electrostatic interaction effects are expected to be particularly relevant for the formation of tilted stacked columns. Specifically, we investigate various structural parameters as well as the melting transition. We find that the second approach yields consistent results with those from experiments despite the fact that the underlying potential decays with the wrong distance dependence at large molecule separations. Our strategy can be transferred to a broader class of molecules, such as benzene or hexabenzocoronene.
在本文中，我们展示并比较了两种不同的、粗粒度的方法来模拟盘状芳香分子（特别是蒄）的静电相互作用。我们的研究基于我们之前的工作 [T. 海涅曼等人，《化学物理杂志》141, 214110 (2014)]，在该工作中，我们基于从原子水平开始的系统粗粒化过程，提出了一种各向异性有效（类盖伊 - 伯恩）势，它能够描述范德华力对相互作用能的贡献。为了考虑静电作用，首先，我们沿着蒄盘的对称轴引入一个线性四极矩。第二种方法考虑了分子内部分电荷呈环状分布这一事实。然后我们对类盖伊 - 伯恩有效势进行重新参数化，使其在短距离内与环 - 环势相匹配。为了研究这两种方法的有效性，我们进行多粒子分子动力学模拟，重点关注晶相（卡帕石），在该相中静电相互作用效应预计对倾斜堆叠柱的形成特别重要。具体而言，我们研究了各种结构参数以及熔化转变。我们发现第二种方法产生的结果与实验结果一致，尽管在大分子间距较大时，其基础势随距离的衰减依赖关系是错误的。我们的策略可以推广到更广泛的一类分子，如苯或六苯并蒄。
