CAREER: Chemical Trends of Elements Under Pressure and their Effects to Forms and Properties of Materials

非技术性总结该职业奖支持通过了解高压下元素的基本化学特性来设计新材料的研究和教育。所有物质都是由元素组成的，所有元素都表现出特殊的化学性质，这取决于它们在周期表中的位置。化学的一般规律是，元素的特性和行为是由原子最外层轨道的电子决定的。我们目前的化学知识和实践受到周期表中元素数量和这些元素可能存在的化学状态的限制。该项目旨在揭示如何利用物理力来打破化学的上述边界。当这种情况发生时，现有的元素可以彻底改变它们的化学特性和身份，并表现得像全新的元素。利用先进的计算技术，该项目将系统地探索通过利用改变元素化学性质的物理压力可以形成的新材料。结合一个新的量子力学模型的原子在有限的空间，这个项目将理解如何压力将改变元素周期表。这项工作通过揭示元素在压力下的变化，可能大大扩展材料的范围。它还可能使人们了解如何利用新化学来设计和获得具有不寻常特性的新材料，以及了解地球和系外行星内部元素的行为和分布。原子和电子结构的计算机模拟将被纳入加州州立大学北岭分校本科生和研究生的早期课程。北岭分校是一所少数族裔服务机构，有大量西班牙裔学生。它还将介绍给当地社区大学和高中学生，为他们提供材料和化学的更深入的了解，以及他们未来职业生涯的新技能和工具。该职业奖支持计算和理论研究，旨在通过了解元素的基本化学特性（如反应性或氧化态）如何在压力下发生变化以及如何利用这些知识来制造具有不寻常和所需特性的材料来推进材料的设计和发现。该计划的灵感来自于最近高压研究发现的一系列惊人现象，例如变得活泼并形成化学键的核心电子，在间隙位置发挥阴离子作用的电子，以及与离子化合物反应而不形成任何化学键的稀有气体。这些现象是令人兴奋的，因为它们不仅在非常基本的水平上改变了化学，而且还可以大大拓宽材料的形式和性质。深入和系统地了解元素在不同压力水平下的行为是必不可少的，但尚未到位。极端条件下材料的这一新兴领域很难使用目前的高压实验直接研究，而且这些方法也很耗时且成本高昂。快速、低成本的计算机模拟可以探索高压，并有可能为实验提供指导。PI将采用基于量子力学和自动晶体结构搜索方法的计算机模拟，通过研究一系列含有重点元素的化合物的稳定性和成键特征来解决这些问题。具体而言，PI将承担以下研究目标，探索：1）内核p和d芯电子的反应性及其与外部压力的关系，以及相应的成键特征和性质; 2）二元3d金属化合物的逆化学现象; 3）压力下的新化学在设计和生产具有最高性能的新材料中的应用; 4）用一小组参数来表示元素在不同压力水平下的化学行为的可能性，特别是元素周期表在高压下是否以及如何变化。该项目通过一系列活动将研究和教育结合起来，包括建立一个新的计算材料课程和实验室;培训和吸引学生参与尖端材料研究;组织午餐论坛和研讨会。此外，其他CSUN研究小组的选定学生将被邀请担任客座研究员，并将计算方法融入自己的研究课题。该教育计划将有助于增加在STEM领域代表性不足的学生的参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis CAREER award supports research and education in designing novel materials by understanding the basic chemical characteristics of elements under high pressure. All matter is composed of elements, and all elements show peculiar chemical properties depending on their positions in the periodic table. A general rule of chemistry is that the characteristics and behaviors of elements are determined by electrons of an atom's outermost orbital. Our current knowledge and practice of chemistry has been limited by the number of elements in the periodic table and the chemical states in which these elements could exist. This project aims to reveal how physical forces can be used to break the above boundary of chemistry. When this happens, the existing elements can drastically change their chemical characteristics and identities and behave like entirely new elements. Using advanced computational techniques, this project will systematically explore the new materials that can be formed by utilizing the physical pressures that alter the chemical properties of elements. Combining with a new quantum mechanics model of atoms in confined space, this project will apprehend how the pressure will transform the periodic table of elements. The work may largely extend the scope of materials by revealing the transformation of elements under pressure. It may also give rise to knowledge of how the new chemistry can be utilized in designing and obtaining new materials with unusual properties as well as in understanding the behavior and distribution of elements in the interior of Earth and extraterrestrial planets. The computer simulations of atomic and electronic structures will be incorporated into the early curriculum of undergraduate and graduate students in California State University Northridge, a minority serving institution with a large Hispanic enrollment. It will also be introduced to local community college and high school students, providing them with a deeper understanding of materials and chemistry and new skills and tools for their future careers. TECHNICAL SUMMARYThis CAREER award supports computational and theoretical research aimed to advance the design and discovery of materials by understanding how the basic chemical character of elements, such as reactivity or oxidation state, can change under pressure and how to utilize this knowledge to make materials with unusual and desired properties. This plan is inspired by a series of striking phenomena uncovered by recent high-pressure research, such as core electrons that become reactive and form chemical bonds, electrons that play the role of anions at the interstitial sites, and noble gases that react with ionic compounds without forming any chemical bond. These phenomena are exciting because they not only alter the chemistry at the very fundamental level, but also can greatly broaden the form and the properties of materials. An in-depth and systematized understanding of how elements behave under different levels of pressure is essential but not yet in place. This emerging area of materials under extreme conditions is difficult to directly study using current high-pressure experiments, and these methods are also time consuming and costly. Rapid and low-cost computer simulation can explore high pressure and have potential to provide guidance to experiment. The PI will employ computer simulations based on quantum mechanics and automatic crystal structure search methods to address these issues by studying the stability and bonding features of a series of compounds containing focused elements. Specifically, the PI will undertake the following research objectives, exploring: 1) the reactivity of inner core p and d core electrons and its relation to external pressures, and the corresponding bonding feature and the properties; 2) a reverse chemistry phenomena of binary 3d metal compounds; 3) the use of the novel chemistry under pressure in designing and producing new materials with superlative properties; 4) the possibility of representing the chemical behavior of elements under different levels of pressure by a small set of parameters, especially whether and how the periodic table changes under high pressure. The project integrates research and education through a set of activities including establishing a new computational materials course and lab; training and involving students in cutting edge materials research; and organizing lunch forums and seminars. Furthermore, selected students in other CSUN research groups will be invited to work as guest researchers and integrate computational methods into their own research topics. The educational plan will help increase the involvement of students who are underrepresented in STEM areas. It includes outreach activities to provide students from underrepresented groups with multiple opportunities to explore materials science research, STEM education, and associated educational and professional pathways.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.