Materially-Predictive Theory of Magnetic Behavior and the Heavy Fermion State

这项研究的目的是利用和扩展能力， 处理降低的磁有序和相关现象， 包括磁光行为，与高度 关联f电子态在接近或处于重态时 费米子态 从本质上讲，我们已经学会了如何展示 相关电子态的磁有序性质， 投射到以站点为中心的基础上。 我们的材料预测 方法包括两个主要阶段：（1）参数在一个 格点模型哈密顿量包含带f杂化和 带f库仑交换是由一系列电子 结构计算和，（2）一个两步序列，以找到 磁有序性质（基态和平衡 行为、磁激励、临界行为） 将模型哈密顿量转换为共振语言 散射理论得到一个有效的多极双离子 互动，然后使用我们开发的各种方法， 在完全从头计算的基础上预测可观察的性质（不 可调节参数或使用的经验信息）。 我们将使用 这种方法来预测的方法和性质的磁性 重费米子态的有序化 感兴趣的实验系统。 我们的方法论将被扩展 包括预测（1）与以下因素相关的增量比热 磁有序，（2）压力效应和弹性性质，（3） 在高磁场中的作用，（4）合金化，包括 稀释F电子种类。 此外，我们还将启动 外显（构型间）相关作用的研究 对磁光行为和导带的影响。 %%% 将进行计算密集型研究， 材料的磁性，其中电子表现为 如果它们的质量是通常质量的许多倍，即所谓的 重费米子系统 这些高度相关的系统是 难以用常规技术治疗。 的 这里提出的计算是唯一的耦合电子 用多体理论对这些系统进行结构计算， 从第一原理描述这些高度相关的系统 approach.

This research is aimed at exploiting and extending capabilities for treating the reduced magnetic ordering and related phenomena, including magneto-optic behavior, associated with the highly correlated f-electron state on approaching or being in the heavy fermion state. Essentially, we have learned how to exhibit magnetic ordering properties in the correlated-electron state by projecting onto a site-centered basis. Our materially-predictive methodology involves two major stages: (1) the parameters in a lattice model hamiltonian containing both band-f hybridization and band-f coulomb exchange are calculated by a sequence of electronic structure calculations and, (2) a two-step sequence for finding the magnetic ordering properties (ground state and equilibrium behavior, magnetic excitations, critical behavior) first transforming the model hamiltonian into the language of resonant scattering theory to get an effective multipolar two-ion interaction and then using various methods we have developed to predict the observable properties on a wholly ab initio basis (no adjustable parameters or empirical information used). We will use this methodology to predict the approach to and nature of magnetic ordering in the heavy fermion state for seveal isostructural systems of experimental interest. Our methodology will be extended to include predicting (1) incremental specific heat associated with magnetic ordering, (2) pressure effects and elastic properties, (3) effects in high applied magnetic fields, (4) alloying including diluting the f-electron species. In addition, we will initiate studies on the role of explicit (interconfigurational) correlation effects on the magneto-optic behavior and on the conduction bands. %%% Computationally-intensive research will be undertaken to study the magnetic properties of materials in which the electrons behave as if their masses are many times their usual mass, ie, so-called heavy fermion systems. These highly correlated systems are difficult to treat using conventional techniques. The calculations proposed here are unique in coupling electronic structure calculations for these systems with many-body theory to describe these highly correlated systems from a first-principles approach.