We discuss a maximally localized Wannier function approach for constructing lattice models from first-principles electronic structure calculations, where the effective Coulomb interactions are calculated in the constrained random-phase-approximation. The method is applied to the 3d transition metals and a perovskite (SrVO_3). We also optimize the Wannier functions by unitary transformation so that U is maximized. Such Wannier functions unexpectedly turned out to be very close to the maximally localized ones.
First-principles Calculation of Effective Onsite Coulomb Interaction of 3d Transition Metals: Constrained Local Density Functional Approach with Maximally Localized Wannier Function
Screened Coulomb interaction calculations: cRPA implementation and applications to dynamical screening and self-consistency in uranium dioxide and cerium
Maximally localized Wannier functions in LaMnO3 within PBE+U, hybrid functionals, and partially self-consistent GW: an efficient route to construct ab-initio tight-binding parameters for e_g perovskites
When the first four spectral moments are considered, spectral features missing in standard Kohn-Sham (KS) density-functional theory (DFT), such as upper and lower Hubbard bands, as well as spectral satellite peaks, can be described, and the bandwidths can be corrected. Therefore, we have devised a \textit{moment-functional based spectral density functional theory} (MFbSDFT) recently. However, many computational tools in theoretical solid state physics, such as the construction of maximally localized Wannier functions (MLWFs), have been developed for KS-DFT and require modifications if they are…
First-principle Wannier functions and effective lattice fermion models for narrow-band compounds
我们提出了一个系统的程序构建有效的晶格费米模型的基础上的第一性原理电子结构计算的窄带化合物。该方法用于一系列过渡金属（TM）氧化物：SrVO $_3$、YTiO $_3$、V $_2$ O $_3$和Y $_2$ Mo $_2$ O $_7$。它由三个部分组成，从LDA开始。(i)用下折法构造了动能哈密顿量。(ii)反问题的解决方案和构造的Wannier函数（WFs）为给定的动能哈密顿量。(iii)在\textit{auxiliary} WF的基础上计算屏蔽库仑相互作用，其中动能项设置为零。最后一步是必要的，以避免重复计算的动能项，这是明确包括在模型中。屏蔽库仑相互作用的计算在一个混合格式。首先，我们评估的屏蔽所造成的占领数的变化和放松的LMTO基函数，使用传统的约束LDA的方法，其中所有矩阵元素的杂交涉及TM $d$轨道被设置为零。然后，我们打开杂交，并评估与RPA中这种杂交变化相关的筛选。屏蔽的第二个通道是非常重要的，并且导致孤立的$t_{2g}$带的有效库仑相互作用的相对小的值。我们讨论了这种筛选的细节，并考虑其频带填充依赖性，频率依赖性，晶格畸变的影响，邻近的其他频带，和模型哈密顿量的维数。
Within this paper we outline a method able to generate truly minimal basis sets which describe either a group of bands, a band, or even just the occupied part of a band accurately. These basis sets are the so-called NMTOs, Muffin Tin Orbitals of order N. For an isolated set of bands, symmetrical orthonormalization of the NMTOs yields a set of Wannier functions which are atom-centered and localized by construction. They are not necessarily maximally localized, but may be transformed into those Wannier functions. For bands which overlap others, Wannier-like functions can be generated. It is show…
Derivation of RKKY Interaction between Multipole Moments in CeB$_6$ by the Effective Wannier Model based on the Bandstructure Calculation
我们研究了CeB-$_6$的电子态，并根据密度泛函理论能带结构计算得到的Ce-$d,s$和B-$p,s$的74轨道有效Wannier模型（包括14个Ce-$f$轨道和60个导电（$c$）轨道）直接计算了RKKY相互作用。利用Wannier模型的$c$带色散和$f$-$c$混合矩阵元，在波矢$q$空间和实空间中得到了$Γ_8$四重子空间中所有15个有效多极矩的真实耦合.两个$Γ_{5g}$四极$(O_{yz},O_{zx},O_{xy})$和$Γ_{2u}$八极$T_{xyz}$耦合最大限度地增强与$q=(π,π,π)$，这自然地解释了在$T_{Q}=3.2$ K的反铁四极排序的第二阶段，也增强与$q=(0,0,0)$相应的弹性软化的$C_{44}$。此外，$Γ_{5u}$八极$T_{x}^β$，$T_{y}^β$和$T_{z}^β$的耦合对于$q=(π,0,0)$，$(0,π,0)$和$(0,0,π)$是相当大的，这产生了Ce $_{x}$ La $_{1-x}$ B $_6$的第IV相的可能候选者的反铁八极排序。RKKY耦合的位间矢量依赖性表现出不同的长程、振荡、各向同性和各向异性行为，这取决于多极矩的类型。本方法使我们能够以无偏的方式提供关于可能的多极有序的信息，并且一旦从能带结构计算中给出$c$态和$f$-$c$混合元，就可以容易地用于其他局域$f$电子材料。
We present a systematic study clarifying an electronic correlation trend of electrides from first principles. By using the maximally localized Wannier function and the constrained random phase approximation, we calculated the electronic correlation strength $(U-U_{nn})/|t|$ of 19 inorganic electrides, where $U$, $U_{nn}$, and $t$ are the effective onsite Coulomb repulsion, nearest-neighbor Coulomb repulsion, and the nearest-neighbor transfer integrals, respectively. The electronic correlation was found to be highly correlated with the dimensionality of the Wannier-function network of anionic e…
We revisit the localized Wannier state description of the twisted bilayer graphene, focusing on the chiral limit. We provide a simple method for constructing such 2D exponentially localized -- yet valley polarized -- Wannier states, centered on the sites of the honeycomb lattice, paying particular attention to maintaining all the unobstructed symmetries. This includes the unitary particle-hole symmetry, and the combination of $C_2\mathcal{T}$ and the chiral particle-hole symmetry. The $C_2\mathcal{T}$ symmetry alone remains topologically obstructed and is not represented in a simple site-to-si…
