压力下固体中的有效库仑相互作用
Effective Coulomb interactions in solids under pressure
摘要：
相关材料对外界刺激非常敏感，如温度或压力。描述这样的系统的电子性质通常需要应用多体技术，有效的低能量问题的精神，哈伯德模型，或其扩展。虽然压力对结构和能带的影响已经在基于密度泛函的方法中得到了广泛的研究，但电子-电子相互作用的压力依赖性迄今为止很少受到关注。作为一个步骤，在最大本地化的Wannier函数和约束随机相位近似的设置内的实际系统的从头算压力研究，我们在本文中研究的范式库仑相互作用的压力依赖性。虽然压缩通常会导致Wannier函数的“扩展”，从而导致传递元素的增长，但我们发现了一种看似违反直觉的趋势，即裸库仑相互作用在压缩下也会增加。我们调和这些行为，呼吁一个半解析紧束缚模型。此外，我们认为，对于这个模型，最大的Wannier本地化的要求是等效的库仑相互作用矩阵元素的最大化。然后，我们将上述第一性原理技术应用于压力下的fcc氢气。虽然我们发现我们的理解裸库仑相互作用的确认，屏蔽强度的诱导变化导致一个有效的一个带模型与哈伯德相互作用，在压力下是非单调的。
英文摘要：
Correlated materials are extremely sensitive to external stimuli, such as temperature or pressure. Describing the electronic properties of such systems often requires applying many-body techniques to effective low energy problems in the spirit of the Hubbard model, or extensions thereof. While the effect of pressure on structures and bands has been investigated extensively within density-functional based methods, the pressure dependence of electron-electron interactions has so far received little attention. As a step toward ab initio pressure studies for realistic systems within a setup of maximally localized Wannier functions and the constrained random phase approximation, we examine in this paper the paradigmatic pressure dependence of Coulomb interactions. While compression commonly causes the "extension" of Wannier functions, and thus transfer elements, to grow, we find the -- seemingly counter-intuitive -- tendency that the bare Coulomb interaction increases under compression as well. We reconcile these behaviors by appealing to a semi-analytical tight-binding model. We moreover argue that, for this model, the requirement of maximal Wannier localization is equivalent to maximizing the Coulomb interaction matrix elements. We then apply the above first principles techniques to fcc hydrogen under pressure. While we find our comprehension of the bare Coulomb interaction confirmed, the induced changes in screening strengths lead to an effective one band model with a Hubbard interaction that is non-monotonous under pressure.
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