We present a generalized framework, renormalized density matrix downfolding (RDMD), to derive systematically improvable, highly accurate, and nonperturbative effective models from ab initio calculations. This framework moves beyond the common role of ab initio calculations as calculating the parameters of a proposed Hamiltonian. Instead, RDMD provides the capability to decide whether a given effective Hilbert space can be identified from the ab initio data and assess the relative quality of ansatz Hamiltonians. Any method of ab initio solution can be used as a data source, and as the ab initio solutions improve, the resultant model also improves. We demonstrate the framework in an application to the downfolding of a hydrogen chain to a spin model, in which we find the interatomic separations for which a nonperturbative mapping can be made even in the strong coupling regime where standard methods fail, and compute a renormalized spin model Hamiltonian that quantitatively reproduces the ab initio dynamics.
Optical Absorption Study by Ab initio Downfolding Approach: Application to GaAs
我们检查是否本质和定量方面的电子激发光谱被正确捕获的一个有效的低能量模型从{ \em从头算}向下折叠计划。首先采用广义梯度近似下的密度泛函计算方法{ \em ab initio}计算了整体电子结构。利用约束密度泛函理论，在最大定域Wannier函数的基础上，通过下折过程构造了费米能级附近能带的低能有效哈密顿量.利用低能求解器计算了扩展哈伯德模型的低能有效哈密顿量的激发态。作为求解器，我们采用Hartree-Fock近似补充考虑电子-空穴相互作用的单激发组态相互作用方法。目前的三阶段方法适用于GaAs，其中八个频带被保留在有效模型后的下折。所得光谱很好地再现了实验结果，表明我们的下折方案提供了一个令人满意的框架的电子结构计算，特别是对于激发和动力学以及基态。
Theory of ab initio downfolding with arbitrary range electron-phonon coupling
NASA Ames Research Center（美国国家航空航天局艾姆斯研究中心）；University of Oxford（牛津大学）；Tamkang University（淡江大学）；University of Southern California（南加州大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of California Berkeley（加州大学伯克利分校）；Kavli Energy NanoScience Institute at Berkeley（加州大学伯克利分校卡弗里纳米科学能源研究所）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；KBR, Inc.（KBR公司）
Comment on 2501.17230 and 2502.00103 "Phonon-mediated electron attraction in SrTiO3 via the generalized Frohlich and deformation potential mechanisms" and "Theory of ab initio downfolding with arbitrary range electron-phonon coupling"
Derivation of Static Low-Energy Effective Models by ab initio Downfolding Method without Double Counting of Coulomb Correlations: Application to SrVO3, FeSe and FeTe
Superconductivity in Electron Liquids: Precision Many-Body Treatment of Coulomb Interaction
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；Department of Physics, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校物理系）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Center for Computational Quantum Physics, Flatiron Institute（西蒙斯平顿研究所计算量子物理中心）；Department of Physics, Columbia University（哥伦比亚大学物理系）
From strong to weak correlations in breathing-mode kagome van der Waals materials: Nb$_3$(F,Cl,Br,I)$_8$ as a robust and versatile platform for many-body engineering
Radboud University（拉德堡德大学）；University of Groningen（格罗宁根大学）；Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam（阿姆斯特丹大学物理学院范德瓦尔斯-泽曼研究所）；Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University（奥胡斯大学跨学科纳米科学中心（iNANO）物理与天文学系）
