Silica Under Water Attack: Surfaces, Defects, and Nano-Structures

该奖项支持理论研究和教育，以了解宏观和纳米尺度下硅水系统过程的物理原理。二氧化硅-水相互作用的强度范围从货车德瓦尔斯到共价键，取决于局部机械和化学条件。外部或内部压力在改变相互作用方面也起着至关重要的作用。二氧化硅在水环境中的机械和光学性质以及水-二氧化硅界面处的电子结构纠缠在一起。基于第一性原理的大规模计算机模拟是预测材料行为的有力工具。本研究开发了以下理论描述：（1）干燥石英表面的稳定性和二氧化硅表面上的水的固-液转变，（2）吸附分子或纳米团簇和水改性的表面缺陷和光学性质，以及（3）二氧化硅纳米孔和通道充满水和由于纳米限制和应力的现象。研究的第二阶段包括（1）改进量子和经典区域之间的界面模型，（2）构建一个计算体系结构，以集成现代计算机代码进行并行计算，以及（3）实现准粒子自洽的所谓GW方法。所作的努力产生了更广泛的影响，在科学和教育两方面都产生了影响。该研究包括在通用公共许可证（GPL）电子结构代码中实现GW方法，以便更大的科学界可以免费使用。在教育方面，学生将接受分析和计算技能应用方面的培训，研究有助于培养对电子结构计算和多尺度建模前沿的广泛兴趣和技能。该研究的各个方面，特别是基础计算技术，构成了PI在她的大学开发的高级物理课程“物理建模和模拟”的主题的一部分。非技术性总结：该奖项支持理论研究和教育，以了解硅水系统中的物理原理基础过程。二氧化硅是一种简单的分子，由一个硅原子和两个氧原子结合在一起。这种物质在自然界中很常见，被认为是沙子或石英。 它是玻璃和混凝土等物质的主要成分。二氧化硅是地壳中含量最丰富的矿物。同样，水是地球表面最丰富的分子之一。提案研究有助于了解这两种常见材料之间的复杂相互作用。研究人员将使用理论和计算工具来研究二氧化硅表面水的电子结构，并能够研究随后发生的化学过程。基于第一性原理的大规模计算机模拟是预测材料行为的有力工具。 所作的努力产生了更广泛的影响，在科学和教育两方面都产生了影响。该研究包括在计算机代码中实现计算方法，该计算机代码可免费提供给更大的科学界。在教育方面，学生将接受分析和计算技能应用方面的培训，研究有助于培养对电子结构计算和多尺度建模前沿的广泛兴趣和技能。研究的各个方面，特别是基础计算技术，构成了PI在她的大学开发的高级物理课程“物理建模和模拟”的主题的一部分。

TECHNICAL SUMMARY:This award supports theoretical research and education into understanding the physical principles underlying processes in silica-water systems at macro- and nano-scale. The strength of silica-water interactions ranges from van der Waals to covalent depending on local mechanical and chemical conditions. External or internal stress also plays a vital role in modifying the interaction. The mechanical and optical properties of silica in aqueous environments and electronic structures at the water-silica interface are entangled. Large-scale computer simulations based on first principles are powerful tools for predicting materials behavior. This research develops theoretical descriptions of (1) stability of dry quartz surfaces and solid-to-liquid transition of water on silica surfaces, (2) surface defects and optical properties modified by adsorbed molecules or nano-clusters and water, and (3) silica nano-pores and channels filled with water and phenomena due to nanoconfinement and stress. The second phase of the research consists of (1) improving models for interfaces between quantum and classical regions, (2) constructing a computing architecture to integrate modern computer codes for parallel computing, and (3) implementing the quasi-particle self-consistent so-called GW method. The effort undertaken has broader impacts with both scientific and educational consequences. The research includes implementing the GW method in a general public license (GPL) electronic structure code so that it is freely available to the larger scientific community. Educationally, students will receive training in the application of both analytical and computational skills and the research helps develop broad interest and skills in the frontiers of electronic structure calculations and multiscale modeling. Aspects of the research, particularly the underlying computational techniques, form part of the subject matter of the advanced physics course ''Physical modeling and simulation'' developed by the PI at her university.NONTECHNICAL SUMMARY:This award supports theoretical research and education into understanding the physical principles underlying processes in silica-water systems. Silica is a simple molecule with one atom of silicon and two atoms of oxygen bound together. The material is common in nature being recognized as sand or quartz. It is a principal component of glass and substances such as concrete. Silica is the most abundant mineral in the earth's crust. Similarly, water is one of most abundant molecules on the Eath's surface. The proposal research helps understand the complex interactions between these two common materials. Researchers will use theoretical and computational tools to study the electronic structure of water on silica surfaces and will be able to investigate the chemical processes that then take place. Large-scale computer simulations based on first principles are powerful tools used for predicting the materials behavior. The effort undertaken has broader impacts with both scientific and educational consequences. The research includes implementing the computational methods in a computer code that it is freely available to the larger scientific community. Educationally, students will receive training in the application of both analytical and computational skills and the research helps develop broad interest and skills in the frontiers of electronic structure calculations and multiscale modeling. Aspects of the research, particularly the underlying computational techniques, form part of the subject matter of the advanced physics course ''Physical modeling and simulation'' developed by the PI at her university.