Heinemann Thomas, Antlanger Moritz, Mazars Martial, Klapp Sabine H L, Kahl Gerhard
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany.
Institut für Theoretische Physik, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria.
J Chem Phys. 2016 Feb 21;144(7):074504. doi: 10.1063/1.4941585.
We investigate the structural properties of a two-dimensional system of ellipsoidal particles carrying a linear quadrupole moment in their center. These particles represent a simple model for a variety of uncharged, non-polar conjugated organic molecules. Using optimization tools based on ideas of evolutionary algorithms, we first examine the ground state structures as we vary the aspect ratio of the particles and the pressure. Interestingly, we find, besides the intuitively expected T-like configurations, a variety of complex structures, characterized with up to three different particle orientations. In an effort to explore the impact of thermal fluctuations, we perform constant-pressure molecular dynamics simulations within a range of rather low temperatures. We observe that ground state structures formed by particles with a large aspect ratio are in particular suited to withstand fluctuations up to rather high temperatures. Our comprehensive investigations allow for a deeper understanding of molecular or colloidal monolayer arrangements under the influence of a typical electrostatic interaction on a coarse-grained level.
我们研究了一种二维椭球形粒子系统的结构特性，这些粒子在其中心带有线性四极矩。这些粒子代表了各种不带电、非极性共轭有机分子的简单模型。使用基于进化算法思想的优化工具，我们首先在改变粒子的纵横比和压力时研究基态结构。有趣的是，我们发现，除了直观预期的T形构型外，还有各种复杂结构，其特征是多达三种不同的粒子取向。为了探索热涨落的影响，我们在相当低的温度范围内进行了恒压分子动力学模拟。我们观察到，具有大纵横比的粒子形成的基态结构特别适合承受高达相当高温度的涨落。我们的全面研究有助于在粗粒度水平上更深入地理解典型静电相互作用影响下的分子或胶体单层排列。
