Computer Simulations of Phase Transitions

技术概述：该奖项支持使用最先进的计算机模拟的理论研究和教育。这项研究补充了传统的理论和实验方法，研究涉及相变的统计物理中的挑战性问题。研究计划的范围是多样化的，广泛地开发方法来研究无法解析处理的系统中的相变。使用的方法包括蒙特卡罗和自旋动力学模拟，这些方法使用了复杂的软件包，研究小组正在对其进行改进。这是正在进行的探索、开发和改进新的大规模模拟方法的重大努力的一部分。一组不同的物理系统被研究，特别关注那些与磁性材料、生长的薄膜、聚合物和蛋白质相关的系统。研究了平衡系统的静态和动态临界现象，其中包括与薄膜生长和上离子扩散(驱动扩散系统)有关的简单非平衡模型。蒙特卡罗模拟被用来探索具有耦合的磁自由度和弹性自由度的模型，具有几何受挫的晶格系统(焦绿石晶格上的磁自旋之间存在本征局部受挫的物理系统)或竞争相互作用，以及具有有限几何形状和相关边界的系统。由此产生的行为与大量发现的行为根本不同，这是研究的主要动机。自旋动力学模拟也被用来探索处于平衡状态的系统的动力学现象。在与薄膜生长相关的模型中研究了非平衡行为，并用蒙特卡罗和动力学蒙特卡罗方法研究了上离子扩散。并将计算结果与理论和实验结果进行了比较。相变行为的发现和解释以及可能出现的新的普遍性分类，与预期的方法论发展相结合，形成了一项具有实质性知识实质的连贯活动。所做的努力具有更广泛的影响，既有科学上的影响，也有教育上的后果。在其他领域也有许多类似的现象，对这些系统的了解也将得到加强。例如，蛋白质折叠的问题与受挫的磁性模型有许多共同之处，例如粗略的能量图景。许多算法的实现和改进都适用于不同领域的广泛模拟。在许多子调查领域(包括化学、生物化学和统计学)，王-朗道抽样的改进具有广泛的适用性。这项研究为研究生提供了广泛的计算机模拟方法培训，并使他们能够在多个相关领域从事科学职业。开展这项工作的模拟物理中心在培养其他机构和佐治亚大学的研究生方面有着良好的记录。由该中心主办的年度研讨会继续提供一个交流想法和信息的论坛。非技术摘要：该奖项支持使用最先进的计算机模拟的研究和教育。这项研究补充了传统的理论和实验方法，研究涉及相变的统计物理中的挑战性问题。研究计划的范围是多样化的，广泛地开发方法来研究无法解析处理的系统中的相变。研究小组正在改进使用复杂软件包的方法。这是正在进行的探索、开发和改进新的大规模计算机模拟方法的重大努力的一部分。一组不同的物理系统被研究，特别关注那些与磁性材料、生长的薄膜、聚合物和蛋白质相关的系统。研究了平衡系统的静态和动态现象，其中包括与薄膜生长和驱动扩散系统有关的简单非平衡模型。计算机模拟用于探索具有有限几何形状和相关边界的系统模型。由此产生的行为与大量发现的行为根本不同，这是研究的主要动机。并将计算结果与理论和实验结果进行了比较。相变行为和可能的新相变的发现和解释与预期的方法论发展相结合，形成了一项具有实质性智力实质的连贯活动。所做的努力具有更广泛的影响，既有科学上的影响，也有教育上的后果。在其他领域也有许多类似的现象，对这些系统的了解也将得到加强。例如，蛋白质折叠的问题与所研究的磁性模型有许多相似之处。计算机模拟方法的许多进展都适用于不同领域的广泛模拟。在许多子研究领域(包括化学、生物化学和统计学)，这些改进当然是适用的。这项研究为研究生提供了广泛的计算机模拟方法培训，并使他们能够在多个相关领域从事科学职业。开展这项工作的模拟物理中心在培养其他机构和佐治亚大学的研究生方面有着良好的记录。中心主办的年度讲习班继续提供交流意见和信息的论坛。

TECHNICAL SUMMARY:This award supports theoretical research and education in the use of state-of-the-art computer simulations. The research complements traditional theoretical and experimental approaches in the study of challenging problems in statistical physics that involve phase transitions. The program of research is diverse in scope, broadly developing methods to study phase transitions in systems that cannot be treated analytically. The methods used include Monte Carlo and Spin Dynamics simulations and these employ sophisticated software packages are being enhanced by the research group. This is part of a significant effort in the ongoing exploration and development and refinement of new large-scale simulation methods. A diverse set of physical systems are examined with particularly attention to those with relevance to magnetic materials, growing films, polymers, and proteins. Both static and dynamic critical phenomena for systems in equilibrium are examined, and this includes simple non-equilibrium models related to film growth and superionic diffusion (driven diffusive systems). Monte Carlo simulations are used to explore models with coupled magnetic and elastic degrees of freedom, lattice systems with geometric frustration (a physical system with intrinsic local frustration between magnetic spins on a pyrochlore lattice) or competing interactions, and systems with finite geometries and associated boundaries. The resulting behavior, which is fundamentally different than that which is found in the bulk, is a primary motivator of the research. Spin dynamics simulations are also used to explore dynamic phenomena for systems in equilibrium. Nonequilibrium behavior is examined in models related to film growth and superionic diffusion is studied using Monte Carlo and Kinetic Monte Carlo methods. The results are compared with those from theory and experiment. The combination of the discovery and explanation of the phase transition behavior and possible new universality classes together with the anticipated methodological developments forms a coherent activity with substantive intellectual substance.The effort undertaken has broader impacts with both scientific and educational consequences. There are many analogous phenomena in other fields, and the understanding of those systems will also be enhanced. For example, the problem of protein folding has much in common, e.g. a rough ?energy landscape?, with magnetic models with frustration. Many of the algorithmic implementations and advances have applicability to a wide range of simulations in different areas. In many sub-areas of investigation (including chemistry, biochemistry, and statistics) the improvements in Wang-Landau sampling are broadly applicable. The research provides training of graduate students in a broad range of computer simulation methods and enables them to pursue scientific careers in multiple related fields. The Center for Simulational Physics where this work is carried out has an excellent record of educating graduate students from other institutions as well as those from The University of Georgia. The annual Workshop hosted by the Center continues to provide a forum for exchange of ideas and information.NONTECHNICAL SUMMARY:This award supports research and education in the use of state-of-the-art computer simulations. The research complements traditional theoretical and experimental approaches in the study of challenging problems in statistical physics that involve phase transitions. The program of research is diverse in scope, broadly developing methods to study phase transitions in systems that cannot be treated analytically. The methods employ sophisticated software packages are being enhanced by the research group. This is part of a significant effort in the ongoing exploration and development and refinement of new large-scale computer simulation methods. A diverse set of physical systems are examined with particularly attention to those with relevance to magnetic materials, growing films, polymers, and proteins. Both static and dynamic phenomena for systems in equilibrium are examined, and this includes simple non-equilibrium models related to film growth and driven diffusive systems. Computer simulations are used to explore models of systems with finite geometries and associated boundaries. The resulting behavior, which is fundamentally different than that which is found in the bulk, is a primary motivator of the research. The results are compared with those from theory and experiment. The combination of the discovery and explanation of the phase transition behavior and possible new phase transitions together with the anticipated methodological developments forms a coherent activity with substantive intellectual substance.The effort undertaken has broader impacts with both scientific and educational consequences. There are many analogous phenomena in other fields, and the understanding of those systems will also be enhanced. For example, the problem of protein folding has much in common with magnetic models studied. Many of the advances in computer simulation methods have applicability to a wide range of simulations in different areas. In many sub-areas of investigation (including chemistry, biochemistry, and statistics) the improvements are certainly applicable. The research provides training of graduate students in a broad range of computer simulation methods and enables them to pursue scientific careers in multiple related fields. The Center for Simulational Physics where this work is carried out has an excellent record of educating graduate students from other institutions as well as those from The University of Georgia. The annual Workshop hosted by the Center continues to provide a forum for exchange of ideas and information.