Energetics and Excitations of Glass-Forming Materials

加州大学伯克利分校的David Chandler获得了化学系化学理论、模型和计算方法计划颁发的奖项，以开展非平衡统计力学领域的研究，特别是阐明玻璃化转变的潜在驱动力和影响。这些是远离平衡的复杂系统的转变，这些转变表现在结构轨迹空间中。理论技术直到最近才允许进行系统的分析，这些技术的结果现在被用于这项研究，以进一步探索从简单到复杂的混合体系中玻璃化转变的分子起源。特别是，这项研究旨在对玻璃中元素激发的能量和结构进行预测理论。它应该回答这些性质如何与玻璃的制备、玻璃对压力的反应以及成分的变化有关。该理论应该具有一定程度的普遍性，以揭示对其他类型材料的影响，做出可以通过实验检验的预测，并在分子模拟得出的明确结果的指导下，使用实际的近似和见解。这项工作处于当代统计物理学的前沿。科学家们早就了解了平衡理论的原理，并利用这些原理设计了有用的有序和规则的凝聚相。例子包括炼油工业中使用的规则溶液理论，以及钢铁工业中使用的成核的奥斯特瓦尔德阶梯规则。但对于动力学捕获的无序固体和纳米团簇--如玻璃--通过驱使液体物质失去平衡而出现的材料，目前还没有类似的基本理解。这项研究致力于改善这一知识差距。特别是关于玻璃，这些材料是受欢迎的和长期稳定的杂质宿主。因此，在考虑安全、稳定地储存放射性废料时，玻璃是首选材料。同样重要或可能更重要的是，二次有机气溶胶(SOA)通常处于玻璃态。它们的变化在大气化学中起主导作用，影响地球气候和人类健康。因此，这项研究解决了与社会中的重大问题有关的问题。它的深远重要性以及它的基本性质使其非常适合激励和培养学生成为科学家。

David Chandler of the University of California, Berkeley is supported by an award from the Chemical Theory, Models and Computational Methods Program in the Chemistry division to carry out research in the area of non-equilibrium statistical mechanics, specifically to elucidate the underlying driving forces and implications of glass transitions. These are transitions of complex systems driven far from equilibrium, transitions manifested in the structure trajectory space. Theoretical techniques have only recently allowed for their systematic analysis, and results from these techniques are now being used in this research to further explore the molecular origins of glass transitions in systems ranging from simple to complex mixtures. In particular, this research aims at predictive theory for the energies and structures of elementary excitations in glass. It should answer how these properties relate to the preparation of the glass, to responses of glass to stress, and to changes in components. The theory should have a degree of generality to reveal implications for other classes of materials, making predictions that can be tested by experiment, and with practical approximations and insights guided by unambiguous results derived from molecular simulation.The work is at the frontier of contemporary statistical physics. Scientists have long understood the principles of equilibrium theory and exploited these principles to design useful ordered and regular condensed phases. Examples include regular solution theory as it is used in the oil-refining industry, and the Ostwald step rule for nucleation used in the steel industry. But no similarly fundamental understanding is yet available for kinetically trapped disordered solids and nanoclusters -- materials, like glass, that emerge by driving liquid matter out of equilibrium. This research is devoted to ameliorating this gap in knowledge. Concerning glasses, in particular, these materials are welcoming and long-term stable hosts for impurities. Glasses are thus materials of choice when contemplating the safe stable storage of radioactive waste materials. Of similar or possibly greater importance, secondary organic aerosols (SOAs) are most often in glassy states. Their transformations play a dominant role in the chemistry of the atmosphere, affecting Earth's climate and human health. This research, therefore, addresses issues pertaining to significant problems in society. Its profound importance together with its fundamental nature makes it superbly appropriate for motivating and training students to become scientists.