A recently published correlated electron pseudopotentials (CEPPs) method has been adapted for application to the 3d-transition metals, and to include relativistic effects. New CEPPs are reported for the atoms Sc$-$Fe, constructed from atomic quantum chemical calculations that include an accurate description of correlated electrons. Dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules are compared with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples (CCSD(T)) calculations. The CEPPs give better results in the correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.
A method is developed for generating pseudopotentials for use in correlated-electron calculations. The paradigms of shape and energy consistency are combined and defined in terms of correlated-electron wave-functions. The resulting energy consistent correlated electron pseudopotentials (eCEPPs) are constructed for H, Li--F, Sc--Fe, and Cu. Their accuracy is quantified by comparing the relaxed molecular geometries and dissociation energies they provide with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples calculations. Errors inherent in the …
Pseudopotentials for Orbital-Free DFT: Capturing Nonlocality and Correcting Functional Approximants
Rutgers University（罗格斯大学）；University of Ibadan（伊巴丹大学）；Jilin University（吉林大学）；East African Institute for Fundamental Research (EAIFR), University of Rwanda（卢旺达大学东非基础研究院）；Lira University（利拉大学）
Internal energies, enthalpies, phonon dispersion curves, and superconductivity of atomic metallic hydrogen are calculated. The (standard) use pseudopotentials in density-functional theory are compared with full (Coulomb)-potential all-electron linear muffin-tin orbital calculations. Quantitatively similar results are found as far as internal energies are concerned. Larger differences are found for phase-transition pressures; significant enough to affect the phase diagram. Electron--phonon spectral functions $α^2 F(ω)$ also show significant differences. Against expectation, the estimated superc…
Local minimum appearing in the interionic pair interactions, when derived from local model pseudopotential, for Al (and some other polyvalent metals) remains as a long standing problem of clear understanding although some attempts are made by different authors. The origin of this feature of local minimum is systematically investigated in this article, considering both the chemical valence, Z, and the core radius, $R_{c}$ as variables. Ashcroft's empty core model is used to describe the interionic pair-potential, because, it depends on these two parameters only. Results of this investigation sh…
We present an efficient implementation of a surface Green's-function method for atomistic modeling of surfaces within the framework of density functional theory using a pseudopotential localized basis set approach. In this method, the system is described as a truly semi-infinite solid with a surface region coupled to an electron reservoir, thereby overcoming several fundamental drawbacks of the traditional slab approach. The versatility of the method is demonstrated with several applications to surface physics and chemistry problems that are inherently difficult to address properly with the sl…
We have implemented recently developed multiple-projector pseudopotentials into the planewave based auxiliary-field quantum Monte Carlo (pw-AFQMC) method. Multiple-projector pseudopotentials can yield smaller planewave cut-offs while maintaining or improving transferability. This reduces the computational cost of pw-AFQMC, increasing its reach to larger and more complicated systems. We discuss the use of non-local pseudopotentials in the separable Kleinman-Bylander form, and the implementation in pw-AFQMC of the multiple-projector optimized norm-conserving pseudopotential ONCVPSP of Hamann. Th…
The generalized pseudopotential theory (GPT) is a powerful method for deriving real-space transferable interatomic potentials. Using a coarse-grained electronic structure, one can explicitly calculate the pair ion-ion and multi-ion interactions in simple and transition metals. Whilst successful in determining bulk properties, in central force metals the GPT fails to describe crystal defects for which there is a significant local volume change. A previous paper [PhysRevLett.66.3036 (1991)] found that by allowing the GPT total energy to depend upon some spatially-averaged local electron density,…
We present an implementation of time-dependent density functional perturbation theory for spin fluctuations, based on planewaves and pseudopotentials. We compute the dynamic spin susceptibility self-consistently by solving the time-dependent Sternheimer equation, within the adiabatic local density approximation to the exchange and correlation kernel. We demonstrate our implementation by calculating the spin susceptibility of representative elemental transition metals, namely bcc Fe, fcc Ni and bcc Cr. The calculated magnon dispersion relations of Fe and Ni are in agreement with previous work. …
Recently, we developed a new method for generating effective core potentials (ECPs) using valence energy isospectrality with explicitly correlated all-electron (AE) excitations and norm-conservation criteria. We apply this methodology to the 3$^{rd}$-row main group elements, creating new correlation consistent effective core potentials (ccECPs) and also derive additional ECPs to complete the ccECP table for H-Kr. For K and Ca, we develop Ne-core ECPs and for the $4p$ main group elements, we construct [Ar]$3d^{10}$-core potentials. Scalar relativistic effects are included in their construction.…
Using first principles calculations, we have studied the structural and elastic properties of SrTMO3 (TM = Rh, Ti, Mo, Zr) under pressure by the plane wave pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA). The optical properties have been investigated under zero pressure. It is observed that the calculated lattice parameters are in good agreement with the available experimental result and previous theoretical results.
The density of electronic states for bulk metals Au and Pd, their surfaces in the form of polycrystalline surface layers of nanometer thickness is investigated. The calculations were performed using density functional theory with pseudopotential in full relativistic approximation. Approximations have been found that provide calculations the density of electronic states of noble metal surfaces that describe the experimentally observed features of XPS spectra of the valence band of these metals.
We propose a non-perturbative $ab$ $initio$ approach to calculate the electrical conductivity of a liquid metal. Our approach is based on the Kubo formula and the theory of electron-phonon coupling (EPC), and unlike the conventional empirical approach based on the Kubo-Greenwood formula, fully takes into account the effect of coupling between electrons and moving ions. We show that the electrical conductivity at high temperature is determined by an EPC parameter $λ_{\mathrm{tr}}$, which can be inferred, non-perturbatively, from the correlation of electron scattering matrices induced by ions. T…
The mechanisms that drive metal-to-insulator transitions (MIT) in correlated solids are not fully understood. For example, the perovskite (PV) SrCoO3 is a FM metal while the oxygen-deficient (n-doped) brownmillerite (BM) SrCoO2.5 is an anti-ferromagnetic (AFM) insulator. Given the magnetic and structural transitions that accompany the MIT, the driver for such a MIT transition is unclear. We also observe that the perovskite metals LaNiO3, SrFeO3, and SrCoO3 also undergo MIT when n-doped via high-to-low valence compositional changes. Also, pressurizing the insulating BM SrCoO2.5 phase, drives a …
We point out the generic competition between the Hund's coupling and the spin-orbit coupling in correlated materials, and this competition leads to an electronic dilemma between the Hund's metal and the relativistic insulators. Hund's metals refer to the fate of the would-be insulators where the Hund's coupling suppresses the correlation and drives the systems into correlated metals. Relativistic Mott insulators refer to the fate of the would-be metals where the relativistic spin-orbit coupling enhances the correlation and drives the systems into Mott insulators. These contradictory trends are…
Correlated electron behavior of metalorganic molecules: insights from density functional theory combined with many-body effects using exact diagonalization
Dynamical mean-field theory (DMFT) has been employed in conjunction with density functional theory (DFT+DMFT) to investigate the metal-insulator transition (MIT) of strongly correlated $3d$ electrons due to quantum confinement. We shed new light on the microscopic mechanism of the MIT and previously reported anomalous subband mass enhancement, both of which arise as a direct consequence of the quantization of V $xz(yz)$ states in the SrVO$_3$ layers. We therefore show that quantum confinement can sensitively tune the strength of electron correlations, leading the way to applying such approache…
Improving electronic structure calculations for practical and technologically-important materials has been a never-ending pursue. This is especially true for transition and post-transition metal oxides for which the current first-principles approaches still suffer various drawbacks. Here we present a hierarchical-hybrid functional approach built on the use of pseudopotentials. The key is to introduce a discontinuity in the exchange functional between core and valence electrons. It allows for treating the localization errors of sp and d electrons differently, which have been known to be an impo…
We report $β$-detected NMR of ion-implanted $^{8}$Li in a single crystal and thin film of the strongly correlated metal LaNiO$_{3}$. In both samples, spin-lattice relaxation measurements reveal two distinct local metallic environments, as is evident from $T$-linear Korringa $1/T_{1}$ below 200 K with slopes comparable to other metals. A small, approximately temperature independent Knight shift of $\sim 74$ ppm is observed, yielding a normalized Korringa product characteristic of substantial antiferromagnetic correlations, but, we find no evidence for a magnetic transition from 4 to 310 K. Two …
First-order melting of a weak spin-orbit Mott insulator into a correlated metal
通过详尽的实验研究确定了弱自旋轨道莫特绝缘体（Sr（1-x）Lax）3 Ir 2 O 7的电子相图。在通过La取代掺杂电子时，电阻率立即崩溃，伴随着由反铁磁绝缘区域和顺磁金属水坑组成的纳米级相分离的窄区域，该纳米级相分离持续到x~0.04。持续的电子掺杂导致突然的一阶相边界，其中Neel态被抑制，并且出现具有增强的自旋磁化率和局部矩的均匀的、相关的金属态。随着金属态的稳定，一个弱的结构扭曲发展，并建议与母自旋轨道莫特态的竞争不稳定性。
Site-polarized Mott phases competing with a correlated metal in twisted WSe$_2$
University of Hamburg（汉堡大学）；The Hamburg Centre for Ultrafast Imaging（汉堡超快成像中心）；University of Würzburg（维尔茨堡大学）；Max Planck Institute for the Structure and Dynamics of Matter（物质结构与动力学马普研究所）；RWTH Aachen University（亚琛工业大学）；Center for Computational Quantum Physics, Flatiron Institute（平顿研究所计算量子物理中心）；Tsientang Institute for Advanced Study, Zhejiang（浙江大学前沿技术研究院（紫江））；Songshan Lake Materials Laboratory（松山湖材料实验室）
The kagome lattice, whose electronic valence band (VB) structure includes two Dirac bands and one flat band, offers a rich space to realise tuneable topological and strongly correlated electronic phases in two-dimensional (2D) and layered materials. While strong electron correlations have been observed in inorganic kagome crystals, they remain elusive in organic systems. The latter offer versatile synthesis protocols via molecular self-assembly and metal-ligand coordination. Here, we report the synthesis of a 2D metal-organic framework (MOF) where di-cyano-anthracene (DCA) molecules form a kag…
