Collaborative Research: Thermodynamics and thermoelasticity of iron-bearing phases

地球和其他类地行星的深层地幔由含铁矿物组成。围绕其他恒星运行的类地行星（类地系外行星），包括大型的超级地球，也必须含有含铁的阶段。这些阶段受到行星深处普遍存在的极端压力和温度的影响。研究它们的热力学和热弹性特性是理解行星形成和演化过程的基本步骤。在研究行星内部结构和动力学时，它也很重要。在这里，研究人员探索了极端条件下地幔含铁相的结构和性质。他们在原子尺度上进行系统的计算，称为从头算，因为他们以量子力学的方式处理电子。他们使用创新的方法来量化铁的电子状态，铁是影响材料性能的关键因素。该团队还对行星动力学进行了数值模拟，以约束地幔演化和现今的结构。该项目的结果对理解地球的地幔动力学具有重要意义，特别是它的热对流，它限制了板块构造和相关的危害。与社区分享的新的模拟方法可以应用于其他材料。这个多学科项目-在材料科学，矿物物理学和地球动力学的十字路口-为博士后和研究生提供支持。它还促进了对本科生和公众的教育推广。在这里，该团队通过汇集强相关电子和地球形成阶段的物理学专家，解决了高压矿物物理学中的一类基本问题。含铁氧化物和硅酸盐含有强相关电子，这对从头计算具有挑战性。这在TPa范围内的压力（数千万大气压）和10,000 K范围内的温度（数万华氏度）下尤其如此。研究人员开发了新的代码来解决这个具有挑战性的问题和随之而来的影响，比如自旋跃迁。他们使用最先进的方法，如自洽密度泛函理论加上哈伯德U （DFT+Usc）和自适应通用算法（AGA）。新代码将作为独立软件或在Quantum ESPRESSO软件的后续版本中发布。这个流行的用于从头开始材料模拟的开源软件拥有广泛的跨学科用户社区。在这项研究过程中产生的结果通过一个公共数据库和互动网站提供。该团队还促进对本科生和公众的教育推广，以及与荷兰和加拿大的国际合作。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The deep mantle of Earth and other solar terrestrial planets consists of iron-bearing minerals. Earth-type planets orbiting other stars (terrestrial exoplanets), including the large super-Earths, must contain iron-bearing phases as well. These phases are subjected to the extreme pressures and temperatures prevailing in deep planetary interiors. Investigating their thermodynamic and thermoelastic properties is a fundamental step toward understanding the processes responsible for planet formation and evolution. It is also important when investigating planet internal structure and dynamics. Here, the researchers explore the structure and properties of mantle iron-bearing phases at extreme conditions. They carry out systematic calculations at the atomic scale, called ab initio because they address electrons quantum mechanically. They use innovative methods to quantify the electronic state of iron, a key player which greatly impacts materials properties. The team also performs numerical simulations of planet dynamics to constrain mantle evolution and present-day structures. The project's outcomes have strong implications for the understanding of Earth's mantle dynamics, notably its thermal convection which constrains plate tectonics and associated hazards. The new simulation methods, shared with the community, can be applied to other materials. This multidisciplinary project - at the crossroad of materials science, mineral physics, and geodynamics - provides support for postdoctoral associates and graduate students. It also fosters educational outreach toward undergraduate students and the public. Here, the team tackles a fundamental class of problems in high-pressure mineral physics by bringing together experts in the physics of strongly correlated electrons and Earth forming phases. Iron-bearing oxides and silicates contain strongly correlated electrons which are challenging for ab initio calculations. This is particularly true at pressures in the TPa range (tens of millions of atm) and temperatures in the 10,000 K range (tens of thousands of degrees Fahrenheit). The researchers develop new codes to address this challenging problem and attendant effects, such as spin transitions. They use state-of-the-art methods such as self-consistent density functional theory plus Hubbard U (DFT+Usc) and an adaptative generic algorithm (AGA). New codes will be release as stand-alone software or in subsequent releases of the Quantum ESPRESSO software. This popular open source software for ab initio materials simulations has a broad community of users across disciplines. Results generated in the course of this research are made available through a public database and interactive websites. The team also fosters educational outreach toward undergraduate students and the public, and international collaboration with the Netherlands and Canada.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.