RUI: Chain Conformation and Collapse in Polymer Systems: Mapping a Many-Body onto a Few-Body Problem

技术概述：该奖项支持理论聚合物物理学的研究和教育。研究重点是溶剂对聚合物链构象的显式影响。由于聚合物的复杂结构，无论是合成的还是生物的，都取决于其存在的流体，因此有必要包括细节（例如，宿主液体中的原子）或采用有效的介质近似来预测聚合物链的构象。在这项工作中进行的研究用适当准确（和更复杂）的有效交互取代了复杂的环境。该方法适用于多尺度建模的一般领域，特别是在聚合物体系中。该方法的有效性范围及其扩展的准确性是研究的主要内容。中心部分的研究工作对聚合物构象和溶剂性质之间的耦合进行了详细的理论理解。一个简单的，但现实的基于连续体的相互作用现场模型被使用，其中聚合物和溶剂都是由“简单液体”单体构建的。该方法通过引入一组位点-位点溶剂化势，将溶剂中多体链问题映射为少体单链问题。这种方法充分地将局部溶剂结构融入到溶剂化势中。该研究从PI最近的工作发展而来，该工作(i)建立了短链在简单液体溶剂中精确多体溶剂化电位的对偶分解的有效性，（ii）成功地将短链溶剂化电位结果应用于长链体系。这些初步结果表明，该方法有可能应用于广泛的系统。该奖项的研究重点是将方法扩展到更大类别的相互作用势，从而更现实的系统，包括不对称系统，其中聚合物和溶剂由不同的相互作用位点构建，以及分子（和聚合物）溶剂系统。在这些体系中，研究了溶剂对链的构象和坍塌的影响，以及多体相关性。所进行的活动具有广泛的影响，超出了具体的研究问题。这项研究是朝着建立一个基于严格的液态物理技术的完整的聚合物液体理论的目标迈出的重要一步。该方法提供了一种直接的方法来解释聚合物体系中的溶剂效应，而无需执行计算上昂贵的全溶剂模拟。这项研究的结果通过在科学期刊上发表和在地方、区域和国家会议上介绍来传播。该研究项目旨在通过与PI学院的物理课程相结合，最大限度地提高学生的参与度。在核心物理课程中教授的计算和模拟方法建立了课堂学习和本研究项目之间的直接联系，并为学生提供了为这项工作做出有意义贡献所需的工具。参与这项研究的本科生将受益于学习最先进的计算机模拟技术，并有机会在科学会议上发言。这项研究延续了指导本科生作为研究人员并成功培养他们进入科学和工程研究生学习的记录。非技术概述：该奖项支持理论聚合物物理学的研究和教育。研究的重点是预测长聚合物在不同溶剂中溶解时的形状。由于聚合物的复杂结构，无论是合成的还是生物的，都取决于其存在的流体，因此有必要包括细节（例如，宿主液体中的数千个原子）或采用近似值来准确预测聚合物链的构象。在这项工作中进行的研究用一套适当精确（和更复杂）的聚合物原子如何相互作用的规则取代了宿主液体的复杂环境。该方法的有效性范围及其扩展的准确性是研究的主要内容。中心部分的研究工作对聚合物形状和溶剂性质之间的耦合进行了详细的理论理解。我们使用了一个简单而现实的模型，其中聚合物和溶剂都是由“简单液体”伪原子构成的。该方法将复杂的溶剂中聚合物问题映射到一个更简单的仅聚合物问题上。所进行的活动具有广泛的影响，超出了具体的研究问题。这个主题具有广泛的重要性，因为溶解聚合物的整体性质，包括聚合物的溶解度，溶液粘度和功能，与单个聚合物分子的潜在微观结构密切相关。这项研究的结果通过在科学期刊上发表和在地方、区域和国家会议上介绍来传播。该研究项目旨在通过与PI学院的物理课程相结合，最大限度地提高学生的参与度。在核心物理课程中教授的计算和模拟方法建立了课堂学习和本研究项目之间的直接联系，并为学生提供了为这项工作做出有意义贡献所需的工具。参与这项研究的本科生将受益于学习最先进的计算机模拟技术，并有机会在科学会议上发表论文。这项研究延续了指导本科生作为研究人员并成功培养他们进入科学和工程研究生学习的记录。

TECHNICAL SUMMARY:This award supports research and education in theoretical polymer physics. The research focus addresses the problem of explicit solvent effects on polymer chain conformation. Because the complex structure of a polymer, whether synthetic or biological, depends on the fluid in which it exists, it is necessary to either include the details (e.g atoms in a host liquid) or employ an effective medium approximation adequate to predict polymer chain conformation. The research carried out in this effort replaces the complex environment by suitably accurate (and more complicated) effective interaction. The approach feeds into the general field of multiscale modeling, especially in polymeric systems. The domain of validity of the approach and the accuracy of its extensions are primary interests of the research.The center piece research effort develops a detailed theoretical understanding of the coupling between polymer conformation and solvent properties. A simple, yet realistic continuum based interaction-site model is used in which both polymer and solvent are built from "simple-liquid" monomers. The approach maps the many-body chain-in-solvent problem onto a few-body single-chain problem via the introduction of a set of site-site solvation potentials. This approach fully incorporates the local solvent structure into the solvation potentials.The research evolves from recent work by the PI that (i) establishes the validity of a pair-wise decomposition of the exact many-body solvation potential for a short chain in a simple-liquid solvent and (ii) successfully applies short chain solvation potential results to long-chain systems. These initial results indicated the potential application to a broad range of systems. The research of this award focuses on the extends the approach to a larger class of interaction potentials and thus more realistic systems, including asymmetric systems in which the polymer and solvent are built from different interaction sites and to systems with molecular (and polymeric) solvents. The effects of solvent on chain conformation and collapse, as well as multi-body correlations, are studied in each of these systems.The activities undertaken have broad impact beyond the specific research problems. This research represents an important step towards the goal of developing a complete theory of polymeric liquids based on the rigorous techniques of liquid state physics. The approach provides a straightforward way to account for solvent effects in polymer systems without having to perform computationally expensive full-solvent simulations. The results of this research are disseminated both through publication in scientific journals and through presentation at local, regional, and national meetings. The research program has been designed to allow for maximum student participation by dovetailing into the physics curriculum at the PI's college. Computation and simulation methods taught in the core physics courses establish a direct link between classroom learning and this research program and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research benefit by learning state of the art computer simulation techniques and have opportunities to present at scientific meetings. This research continues a track record of mentoring undergraduates as researchers and successfully fostering their advancement to graduate study in science and engineering. NONTECHNICAL SUMMARY:This award supports research and education in theoretical polymer physics. The research focus addresses the problem of predicting the shape of long polymers when dissolved in different solvents. Because the complex structure of a polymer, whether synthetic or biological, depends on the fluid in which it exists, it is necessary to either include the details (e.g thousands of atoms in a host liquid) or employ an approximation to accurately predict polymer chain conformation. The research carried out in this effort replaces the complex environment of the host liquid by suitably accurate (and more complicated) set of rules for how the atoms of polymer interact with each other. The domain of validity of the approach and the accuracy of its extensions are primary interests of the research.The center piece research effort develops a detailed theoretical understanding of the coupling between polymer shape and solvent properties. A simple, yet realistic model is used in which both polymer and solvent are built from "simple-liquid" pseudo-atoms. The approach maps the complex polymer-in-solvent problem onto a simpler polymer-only problem.The activities undertaken have broad impact beyond the specific research problems. This topic is of broad importance since the overall properties of dissolved polymers, including polymer solubility, solution viscosity, and functionality, are intimately linked to the underlying microscopic configuration of the individual polymer molecules. The results of this research are disseminated both through publication in scientific journals and through presentation at local, regional, and national meetings. The research program has been designed to allow for maximum student participation by dovetailing into the physics curriculum at the PI's college. Computation and simulation methods taught in the core physics courses establish a direct link between classroom learning and this research program and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research benefit by learning state-of-the-art computer simulation techniques and have opportunities to present papers at scientific meetings. This research continues a track record of mentoring undergraduates as researchers and successfully fostering their advancement to graduate study in science and engineering.