强关联f电子材料磁激发谱的第一原理计算方法研究

强关联f电子材料的基态电子结构异常复杂，其低能集体激发行为更是异彩纷呈，长期以来备受关注。非弹性中子散射可以用于测量磁激发谱，目前进展十分显著，但是相应的理论计算工作却踯躅不前。本项目拟聚焦于磁激发谱与自旋动力学的第一原理计算方法，研究以下内容: (1)以密度泛函理论结合动力学平均场理论为基础，重点突破双粒子格林函数的高频行为模拟、磁化系数的解析延拓、Bethe-Salpeter方程的迭代求解等关键技术，发展一套适用于强关联f电子材料的磁激发谱的第一原理计算方法。(2)计算典型强关联f电子材料(包括拓扑绝缘体CeNiSn、Weyl-Kondo半金属Ce3Bi4Pd3、重费米子化合物URu2Si2、Mott绝缘体CmO2、变价元素Cf)的磁激发谱，探索f电子结构与自旋动力学的联系。本项目的研究成果将促进对f电子反常行为的了解，提升第一原理计算方法对于强关联材料电子结构的描述能力。

Strongly correlated f-electron materials usually exhibit complex ground state electronic structures and exotic low-energy collective excitations. Since the last decades, they have attracted a lot of attentions. It is well known that the inelastic neutron scattering could be used to detect the magnetic excitation spectra of strongly correlated f-electron materials, and some remarkable results have been obtained. However, theoretical descriptions for the magnetic excitation spectra of strongly correlated f-electron materials are not well established so far. This proposal will concentrate on the theoretical methods for magnetic excitations and spin dynamics. The major tasks are as follows: (1) We would like to implement a new first-principles approach for calculating the magnetic excitation spectra of strongly correlated f-electron materials. This approach will rely on the combination of density functional theory and dynamical mean-field theory. The long-standing problems, such as the evaluation of high-frequency asymptotic behavior of two-particle Green’s function, analytical continuation of dynamical magnetic susceptibility, and numerical stability of Bethe-Salpeter equation iteration solver, will be carefully tackled. (2) The magnetic excitation spectra of some typical strongly correlated f-electron materials, including Mobius topological insulator CeNiSn, Weyl-Kondo semimetal Ce3Bi4Pd3, heavy fermion compound URu2Si2, Mott insulator CmO2, and mixed-valence element Cf will be calculated by the new approach. The relationship between the f electronic configurations and spin dynamics will be revealed. This project will enrich our understandings about the unusual characters of 4f and 5f electrons. The ability of first-principles many-body approach for studying the intriguing properties of strongly correlated f-electron materials will be enhanced as well.