Tuning Reactivity, Electronic Structure and Properties via Pressure: Predicting Novel Superconductors

该奖项支持研究和教育，其最终目标是通过计算建模合理设计新的超导体，即电流可以在不损失能量的情况下流动的材料。用超导电力线取代铜线将对美国的电力基础设施产生巨大影响，但不幸的是，所有目前已知的超导体在成为超导之前都必须冷却到非常低的温度。研究表明，富氢固体可能在高温下表现为超导体，因此它们将成为这个项目的重点。就像钻石可以在地球内部的高压下合成一样，研究人员可以利用压力作为一个变量来创造出具有不同寻常特性的新材料，这些材料在压力释放后可能保持稳定。用这种方法合成了许多新的超导体。然而，由于这些实验很难进行，计算预测可以加速新材料的发现。PI将基于量子力学进行计算，以预测有希望的合成新目标，并与领先的实验小组合作进行高压研究，试图合成这些材料。为了实现这一目标，PI将进一步开发一套软件工具，可用于在没有任何实验信息的情况下计算预测固体的结构。这些工具可以免费提供给材料科学、物理和化学社区，从而促进合理的材料设计以及科学和工程领域当前和未来的发现。研究生和本科生将接受合理的计算材料设计和编程方面的训练，从而为他们未来的职业生涯做好准备，在理论，计算和实验之间的协同作用导致创新。与主要为本科生和少数民族服务的机构（加州州立大学圣贝纳迪诺分校）的学生和教师交流将使这些学生接触到STEM领域的研究和未来的职业机会，并培训他们掌握最先进的材料建模技术。该奖项支持理论研究和教育，这些研究和教育将导致新型超导体的合理设计。PI将通过计算预测具有独特化学计量和结构的材料的晶体结构，这些材料可以利用压力变量合成，并通过第一性原理计算研究它们的电子结构和性质。重点将放在含有氢掺杂p块元素的化合物上，因为p块原子之间的强共价键可能使这些结构在减压到大气压时变成亚稳态，并且实验和理论都表明二元氢化物可能具有很高的超导转变温度。PI还将研究二元极性金属间化合物，因为已经证明，其中许多可以在适度的压力下合成，在大气条件下保持稳定，并表现为BCS超导体。新的，也许是完全意想不到的，化学和全新类型的材料将在理论上被发现，这些预测将被高压研究的主要实验小组证实。该合同还将支持“XtalOpt”进化算法的进一步发展，该算法可用于预测仅给定其化学计量的扩展系统的结构。关键的发展将增加可以在没有任何实验信息的情况下预测的单元格的大小和复杂性，并加速扩展系统的先验结构预测的进展。高度流行的化学构建器、编辑器和可视化器“阿伏伽德罗”中的晶体学套件将进一步发展。因为XtalOpt和Avogadro是在开源促进会批准的许可下编写的，所以程序代码可以重复使用，从而为网络基础设施以及当前和未来的科学和工程发现做出贡献。研究生和本科生将接受合理的计算材料设计和编程方面的训练，从而为他们未来的职业生涯做好准备，在理论，计算和实验之间的协同作用导致创新。与主要为本科生和少数民族服务的机构（加州州立大学圣贝纳迪诺分校）的学生和教师交流将使这些学生接触到STEM领域的研究和未来的职业机会，并培训他们掌握最先进的材料建模技术。

NON-TECHNICAL SUMMARYThis award supports research and education whose ultimate goal is to rationally design new superconductors, materials through which electric current can flow without losing energy, via computational modeling. Replacing copper wires with superconducting power lines would have a tremendous impact on the electrical power infrastructure of the USA, but unfortunately all of the currently known superconductors must be cooled down to very low temperatures before they become superconducting. Research suggests that hydrogen-rich solids could potentially behave as superconductors at high temperatures, and they will therefore be the focus of this project.Just like diamond can be synthesized at high pressure within the earth, researchers can use pressure as a variable to create new materials with unusual properties that may remain stable when the pressure is released. A number of new superconductors have been synthesized in this way. However, since these experiments are very difficult to perform, computational predictions can accelerate new materials discovery. The PI will carry out calculations based upon quantum mechanics to predict promising new targets for synthesis, and collaborate with leading experimental groups in high-pressure research that will attempt to synthesize these materials. To advance this goal the PI will further develop a set of software tools, which can be used to computationally predict the structure of a solid without any experimental information. These tools are made freely available to the materials science, physics and chemistry communities, thereby advancing rational materials design as well as current and future discoveries in science and engineering. Graduate and undergraduate students will be trained in rational computational materials design and programming, thereby preparing them for future careers where synergy between theory, computation and experiment leads to innovation. Student and faculty exchange with a primarily undergraduate, minority serving institution (California State University San Bernardino) will expose these students to research and future career opportunities in STEM fields, and train them in state-of-the-art materials modeling techniques. TECHNICAL SUMMARYThis award supports theoretical research and education that will lead towards the rational design of novel superconductors. The PI will computationally predict the crystal structures of materials with unique stoichiometries and structures that can be synthesized using the pressure variable, and study their electronic structures and properties via first-principles calculations. Focus will be placed on compounds containing hydrogen doped with a p-block element because strong covalent bonds between the p-block atoms may render these structures metastable upon decompression to atmospheric pressures, and both experiment and theory suggest that binary hydrides may have a high superconducting transition temperature. The PI will also study binary polar intermetallics, as it has already been demonstrated that many of these can be synthesized at modest pressures, remain stable at atmospheric conditions, and behave as BCS superconductors. New, perhaps completely unexpected, chemistry and totally new types of materials will be discovered theoretically, and the predictions will be confirmed by leading experimental groups in high pressure research. The award will also support the further development of the "XtalOpt" evolutionary algorithm, which can be used to predict the structure of an extended system given only its stoichiometry. Key developments will increase the size and complexity of the unit cells that can be predicted without any experimental information, and accelerate the progress of a priori structure prediction for extended systems. The crystallography suite within the highly popular chemical builder, editor and visualizer "Avogadro", will be further advanced. Because XtalOpt and Avogadro are written under licenses approved by the Open Source Initiative, the program code can be re-used, thereby contributing towards cyberinfrastructure as well as current and future discoveries in science and engineering. Graduate and undergraduate students will be trained in rational computational materials design and programming, thereby preparing them for future careers where synergy between theory, computation and experiment leads to innovation. Student and faculty exchange with a primarily undergraduate, minority serving institution (California State University San Bernardino) will expose these students to research and future career opportunities in STEM fields, and train them in state-of-the-art materials modeling techniques.