论文标题
在密度功能理论中建模磁多极相
Modelling Magnetic Multipolar Phases in Density Functional Theory
论文作者
论文摘要
相关绝缘子中的多极磁相对于密度功能理论（DFT）的巨大挑战，这是由于相互作用的相互作用的共存，通常是自旋轨道耦合，晶体场以及复杂的非共线和高级别间交换，创建了一个与多个最小值的配置配置。尽管对DFT的 +u校正原则上允许对这种磁接地态的建模，但其结果很大程度上取决于最初的对称性破坏，从而限制了收敛的DFT +U解决方案中订单参数的性质。通常，DFT+U从一组初始的现场磁矩开始导致常规偶极阶。在磁多极排序的情况下，显然需要一种更复杂的方法，这是由于磁化原子上以磁原子为中心的球的磁化密度的无效积分所揭示的，但局部贡献非零。在这里，我们展示了如何使用受过教育的有限的原始密度矩阵初始化有效地捕获此类阶段，该矩阵源自从头算有效的哈密顿式的多极订购的基态。因此，这种异国情调的基态的各种特性，例如其单电子光谱，因此可以通过全电子DFT+U方法访问。我们在最近预测的ba $ _2 $ moso $ _6 $（m = ca，mg，Zn）[Phys。莱特牧师。 127，237201（2021）]
Multipolar magnetic phases in correlated insulators represent a great challenge for Density Functional Theory (DFT) due to the coexistence of intermingled interactions, typically spin-orbit coupling, crystal field and complex non-collinear and high-rank inter-site exchange, creating a complected configurational space with multiple minima. Though the +U correction to DFT allows, in principle, the modelling of such magnetic ground states, its results strongly depend on the initially symmetry breaking, constraining the nature of order parameter in the converged DFT+U solution. As a rule, DFT+U calculations starting from a set of initial on-site magnetic moments result in a conventional dipolar order. A more sophisticated approach is clearly needed in the case of magnetic multipolar ordering, which is revealed by a null integral of the magnetization density over spheres centered on magnetic atoms, but with non-zero local contributions. Here we show how such phases can be efficiently captured using an educated constrained initialisation of the onsite density matrix, which is derived from the multipolar-ordered ground state of an ab initio effective Hamiltonian. Various properties of such exotic ground states, like their one-electron spectra, become therefore accessible by all-electron DFT+U methods. We assess the reliability of this procedure on the Ferro-Octupolar ground state recently predicted in Ba$_2$MOsO$_6$ (M = Ca, Mg, Zn) [Phys. Rev. Lett. 127, 237201 (2021)]
