Superconductivity and Other Quantum Orderings in the Lighter Elements

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。技术概要：该奖项支持理论研究和教育，主要集中在轻元素，包括在高压和高温条件下的氢。PI的目的是阐明量子排序，无论是在氢和氢合金与其他轻元素系统。在这些系统中，超导性的重要基础和实用领域日益突出，这是由最近在硅烷的金属态中发生的超导性的相当戏剧性的发现所推动的。这可能是一种可能性，已经提出了研究支持以前的赠款和同伴的预测，迄今为止的“简单”的元素将采取相当复杂的结构在类似的条件下也迅速证实了实验。值得注意的是，许多迄今为止被认为是“简单”的元素被观察到在更高密度下占据结构，甚至表现出不可分解性。研究的一个主要主题是由实验高压物理学的最新进展所激发的。PI旨在阐明超导态的物理学，特别是电子涨落在多带和准局域背景下的作用。长期以来，人们一直预测高温超导性发生在氢的金属相中，最近又预测发生在氢占主导地位的金属合金中。这类系统的理论的进一步发展似乎是有序的，特别是探索可能伴随亚晶格熔化的进一步有序化的可能性。对于纯氢本身，超流性和超导性的共存已经被预测为液态金属（近）基态，现在将理论扩展到液态金属氘所体现的混合对称系统是一个有趣的途径，再次着眼于实验实现。在电子术语中，所有这些系统都是高度不均匀的，正如尖点定理所保证的那样，这项工作将继续发展加权密度和相关的方法，以达到相关电子结构的密度泛函观点，并有助于阐明从金属态到绝缘或半导体态的转变的物理学。该奖项支持凝聚态物理学的理论研究和教育，主要集中在轻元素，包括极端压力和温度下的氢。 这项工作的一个关键特征是预测在实验中可以观察到的关键签名。虽然在巨大压力下的氢存在于我们太阳系的各个地方和宇宙的其他地方，但实验高压技术的最新进展表明，发现具有潜在技术应用的令人兴奋的新物质相即将到来。其中的可能性是超导状态，发生在高温下的轻元素在高压下。PI将继续并扩展他的理论工作，以预测和探索可能出现在看似最简单的元素中的新物质状态。高压下的氢和以氢为主的金属合金将是工作的特别重点。这项研究可能会对其他学科产生影响，并将为未来的科学家提供培训基地。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARY: This award supports theoretical research and education focused mainly on the light elements, including hydrogen under conditions of high pressure and high temperature. The PI aims to elucidate quantum orderings, both in hydrogen and in hydrogen alloyed with other light element systems. Of increasing prominence in these systems is the enduringly fundamental and pragmatic area of superconductivity, impelled by the recent and quite dramatic discovery of superconductivity occurring in the metallic state of silane. That this could be a possibility was already raised in research supported by the previous grant and companion predictions that the hitherto 'simple' elements would adopt structures of considerable complexity at similar conditions were also swiftly borne out by experiment. It is remarkable that many of the elements hitherto regarded as 'simple' are observed to take up structures at higher densities even exhibiting incommensurabilities. A major theme of the research is spurred by striking recent advances in experimental high pressure physics. The PI aims to elucidate the physics of the superconducting state, and particularly the role of electronic fluctuation in multi-band and quasi-localized contexts. High temperature superconductivity has long been predicted to occur in metallic phases of hydrogen and now more recently in hydrogen dominant metallic alloys. Further development of the theory for this class of system seems in order, especially to explore the possibility of further orderings that might accompany sublattice melting. For pure hydrogen itself, co-existence of superfluidity and superconductivity has been predicted for liquid metallic (near) ground states, and extension of the theory now to the mixed symmetry system embodied by liquid metallic deuterium is an interesting avenue to pursue, again with an eye towards experimental realization. In electronic terms all of these systems are highly inhomogeneous, as guaranteed by the cusp theorem, and this work will continue the development of weighted density and related approaches to the density functional viewpoint of the associated electronic structures, and could help illuminate the physics of transitions from the metallic state back to insulating or semiconducting.NON-TECHNICAL SUMMARY: This award supports theoretical research and education in condensed matter physics focused mainly on the light elements, including hydrogen under extremes of pressure and temperature. A key feature of this work is the prediction of key signatures that could be observed in experiments. While hydrogen under enormous pressure exists in various places in our solar system and elsewhere in the universe, recent advances in experimental high pressure techniques suggest that the discovery of exciting new phases of matter with potential technological applications is coming within grasp. Among the possibilities are superconducting states that occur at high temperature in the light elements under high pressure. The PI will continue and extend his theoretical work to predict and explore new states of matter that may emerge in the seemingly simplest elements. Hydrogen and hydrogen-dominant metallic alloys under high pressure will be a particular focus of the work. This research may have impact on other disciplines and will provide a training ground for future scientists.