First-Principles Simulations of Mixtures in Giant Planets

该项目是对巨行星内部特有的高压下分子和原子相互作用的理论研究。将采用两种不同的第一性原理计算方法-密度泛函分子动力学和路径积分蒙特卡罗方法，（1）模拟冰和金属氢之间的界面，以了解它们的稳定性，特别是与巨行星形成和核心生长有关的界面;（2）模拟氢-氦混合物，以了解氦雨及其对土星冷却和辐射光度的影响;（3）预测氦雨封存氖的过程中，土星大气层中氖的消耗程度;（4）计算巨行星内部的状态方程，着眼于解释令人惊讶的大尺寸“热彗星”，并改进木星本身的温度分布;（5）计算H-He混合物的电导率，以更好地理解巨行星中磁场的产生和潮汐扰动的欧姆耗散。一名研究生将在该项目中得到支持和培训，该项目还将为系外行星建模制作高精度状态方程表。这些状态方程将提供给研究界。PI和合作者还将制作一个名为“Planet Builder”的互动网站，学生和公众可以通过该网站了解行星的内部组成和物理条件如何影响行星的整体特征，并与太阳系中的行星进行比较。

This project is a theoretical study of molecular and atomic interactions at the high pressures characteristic of the interiors of giant planets. Two different first-principles computational approaches---density functional molecular dynamics and path integral Monte Carlo---will be used, to (1) simulate interfaces between ice and metallic hydrogen to understand their stability, particularly as related to giant planet formation and core growth; (2) simulate hydrogen-helium mixtures to understand helium rain and its effect of the cooling and radiated luminosity of Saturn; (3) predict the degree to which neon is depleted in Saturn's atmosphere through the process of neon sequestration by helium rain; (4) calculate equations of state for giant planet interiors, with an eye toward explaining the surprisingly large sizes of "hot Jupiters" and refining the temperature profile of Jupiter itself; and (5) calculate the electrical conductivity of H-He mixtures to better understand magnetic field generation and ohmic dissipation of tidal perturbations in giant planets. A graduate student will be supported and trained in this project, which will also produce high-accuracy tables of equations of state for exoplanet modeling. These equations of state will be made available to the research community. The PI and collaborators will also produce an interactive website called "Planet Builder" where students and the public can see how interior composition and physical conditions influence the overall characteristics of planets, in comparison with those in the Solar System.