New Emergent Quantum States of Matter at High Pressure

在常温下，轻碱金属Li、Na和K为近自由电子(NFe)金属。但是，由于离子和电子相互作用的密度驱动变化，这些金属不是像压缩时那样变得更自由电子，而是经历了不寻常和复杂的结构和电子形式的转变。虽然这种行为在所有高密度物质中都是预期的，但这种物理行为在碱金属中最为明显，因为它们在环境条件下的NFE行为，以及它们非常高的可压缩性。因此，它们提供了一个独特的洞察所有其他金属在非常高的密度下的行为。我们将利用我们团队在实验高压物理方面的专业知识，以前所未有的密度创造固体和液体碱金属，然后在同步加速器、x射线自由电子激光和高能激光设施中使用x射线衍射技术来确定它们的结构行为。然后，我们将使用电子结构和量子分子动力学计算来理解所观察到的行为背后的物理学，从而发展对超高密度物质行为的新理解和改进的预测能力。

At ambient conditions, the light alkali metals Li, Na and K are nearly free electron (NFE) metals. But rather than becoming MORE free-electron like when compressed, these metals undergo transitions to unusual and complex structural and electronic forms as a result of density-driven changes in the interactions of the ions and electrons. While such behaviour is expected in all high-density matter, the physics is most evident in the alkali metals due to their NFE behaviour at ambient conditions, and their very high compressibilities. They thus offer a unique insight into the behaviour of all other metals at very high densities. We will exploit our team's expertise in experimental high-pressure physics to create solid and fluid alkali metals at unprecedented densities, and then determine their structural behaviour using x-ray diffraction techniques at synchrotrons, x-ray free electron lasers, and high-energy laser facilities. We will then use electronic structure and quantum-molecular-dynamics calculations to understand the physics behind the observed behaviour, and thereby develop new understanding and improved predictive capabilities in the behaviour of matter at ultra-high densities.