Database of Wannier tight-binding Hamiltonians using high-throughput density functional theory (original) (raw)
Related papers
Physical Review B, 2006
A versatile method for combining density functional theory (DFT) in the local density approximation (LDA) with dynamical mean-field theory (DMFT) is presented. Starting from a general basis-independent formulation, we use Wannier functions as an interface between the two theories. These functions are used for the physical purpose of identifying the correlated orbitals in a specific material, and also for the more technical purpose of interfacing DMFT with different kinds of band-structure methods (with three different techniques being used in the present work). We explore and compare two distinct Wannier schemes, namely the maximally-localized-Wannier-function (MLWF) and the N-th order muffin-tin-orbital (NMTO) methods. Two correlated materials with different degrees of structural and electronic complexity, SrVO3 and BaVS3, are investigated as case studies. SrVO3 belongs to the canonical class of correlated transition-metal oxides, and is chosen here as a test case in view of its simple structure and physical properties. In contrast, the sulfide BaVS3 is known for its rich and complex physics, associated with strong correlation effects and low-dimensional characteristics. New insights into the physics associated with the metal-insulator transition of this compound are provided, particularly regarding correlation-induced modifications of its Fermi surface. Additionally, the necessary formalism for implementing self-consistency over the electronic charge density in a Wannier basis is discussed.
2020
We present a scheme to construct atomic Wannier orbitals which maximally hybridizes naturally by construction through a self-consistently chosen gauge, and capable of incorporating the effects of local atomic environment. These orbitals not only allow accurate extraction of multi-orbital tight-binding(TB) parameters well beyond the nearest neighbourhood, but more importantly, facilitate easy multi-orbital mapping of electronic structure from smaller reference systems to larger target systems with similar variety of atomic neighbourhood, based on projected Wannier centres learned from reference systems. The mapping renders electronic structure of large systems not only at the mean-field level of Kohn-Sham density functional theory(DFT), but also facilitate effective transfer of self-energy correction estimated within the GW approximation of many-body perturbation theory, from smaller reference systems to larger target systems, explicit computation of which would otherwise be prohibitively expensive. Such a bottom-up transferability of TB parameters at the DFT+GW level in the multi-orbital basis made of the proposed maximally hybridized atomic Wannier orbitals demonstrated in a representative variety of two and three dimensional systems, is expected to substantially reduce the computational cost of accurate estimation of electronic structure of large systems with hundreds of atoms.
Multiscale Simulation Methods for Nanomaterials, 2007
Fullerene like cages and naonotubes of carbon and other inorganic materials are currently under intense study due to their possible technological applications. First principle simulations of these materials are computationally challenging due to large number of atoms. We have recently developed a fast, variational and fully analytic density functional theory (ADFT) based model that allows study of systems larger than those that can be studied using existing density functional models. Using polarized Gaussian basis sets (6-311G**) and ADFT, we optimize geometries of large fullerenes, fullerene-like cages and nanotubes of carbon, boron nitride, and aluminum nitride containing more than two thousand atoms. The calculation of C2160 using nearly 39000 orbital basis functions is the largest calculation on any isolated molecule reported to-date at this level of theory, and it includes full geometry optimization. The electronic structure related properties of the inorganic cages and other carbon fullerenes have been studied. Computer simulations are playing increasingly important role in our understanding about materials. Generally, the choice of computational models that are employed in studying the properties of materials depend on the property of interest and the length scale or the size of the system[1]. The latter is the most important factor in the selection of appropriate level of theory. Our interest is in the electronic and structural properties of large carbon fullerenes and fullerene like cages of aluminum and boron nitride containing a few hundred atoms. At these sizes, the current toolbox of methods that are available include semiempirical quantum mechanical models such as ZINDO[2], PM3[3] methods or tight binding approaches[4]. More accurate description of electronic properties require use of more involved meth- * Electronic address: rzope@alchemy.nrl.navy.mil † Electronic address: dunlap@nrl.navy.mil
A Hartree-Fock ab initio band-structure calculation employing Wannier-type orbitals
An ab initio Wannier-function-based approach to electronic ground-state calculations for crystalline solids is outlined. In the framework of the linear combination of atomic orbitals method the infinite character of the solid is rigorously taken into account. The Hartree-Fock ground-state energy, cohesive energy, lattice constant and bulk modulus are calculated in a fully ab initio manner as it is demonstrated for sodium chloride, NaCl, using basis sets close to the Hartree-Fock limit. It is demonstrated that the Hartree-Fock band-structure can easily be recovered with the current approach and agrees with the one obtained from a more conventional Bloch-orbital-based calculation. It is argued that the advantage of the present approach lies in its capability to include electron correlation effects for crystalline insulators by means of well-established quantum chemical procedures.
Journal of Physics: Condensed Matter
The accurate prediction of band gaps and structural properties in periodic systems continues to be one of the central goals of electronic structure theory. However, band gaps obtained from popular exchange-correlation functionals (such as LDA and PBE) are severely underestimated partly due to the spurious self-interaction error (SIE) inherent to these functionals. In this work, we present a new formulation and implementation of Wannier function-derived Fermi-Lowdin (WFL) orbitals for correcting the SIE in periodic systems. Since our approach utilizes a variational minimization of the self-interaction energy with respect to the Wannier charge centers, it is computationally more efficient than the HSE hybrid functional and other self-interaction corrections that require a large number of transformation matrix elements. Calculations on several (17 in total) prototypical molecular solids, semiconductors, and wide-bandgap materials show that our WFL self-interaction correction approach gives better band gaps and bulk moduli compared to semilocal functionals, largely due to the partial removal of self-interaction errors.
A high-throughput infrastructure for density functional theory calculations
Computational Materials Science, 2011
The use of high-throughput density functional theory (DFT) calculations to screen for new materials and conduct fundamental research presents an exciting opportunity for materials science and materials innovation. High-throughput DFT typically involves computations on hundreds, thousands, or tens of thousands of compounds, and such a change of scale requires new calculation and data management methodologies. In this article, we describe aspects of the necessary data infrastructure for such projects to handle data generation and data analysis in a scalable way. We discuss the problem of accurately computing properties of compounds across diverse chemical spaces with a single exchange correlation functional, and demonstrate that errors in the generalized gradient approximation are highly dependent on chemical environment.
First-principles Wannier functions and effective lattice fermion models for narrow-band compounds
Physical Review B, 2006
We propose a systematic procedure for constructing effective lattice fermion models for narrowband compounds on the basis of first-principles electronic-structure calculations. The method is illustrated for the series of transition-metal (TM) oxides: SrVO3, YTiO3, V2O3, and Y2Mo2O7, whose low-energy properties are linked exclusively to the electronic structure of an isolated t2g band. The method consists of three parts, starting from the electronic structure in the local-density approximation (LDA). (i) construction of the kinetic-energy Hamiltonian using formal downfolding method. It allows to describe the band structure close to the Fermi level in terms of a limited number of (unknown yet) Wannier functions (WFs), and eliminate the rest of the basis states. (ii) solution of an inverse problem and construction of WFs for the given kinetic-energy Hamiltonian. Here, we closely follow the construction of the basis functions in the liner-muffin-tin-orbital (LMTO) method, and enforce the orthogonality of WFs to other band. In this approach, one can easily control the contributions of the kinetic energy to the WFs. (iii) calculation of screened Coulomb interactions in the basis of auxiliary WFs. The latter are defined as the WFs for which the kinetic-energy term is set to be zero. Meanwhile, the hybridization between TM d and other atomic states is well preserved by the orthogonality condition to other bands. The use of auxiliary WFs is necessary in order to avoid the double counting of the kinetic-energy term, which is included explicitly in the model Hamiltonian. In order to calculate the screened Coulomb interactions we employed a hybrid approach. First, we evaluate the screening caused by the change of occupation numbers and the relaxation of the LMTO basis functions, using the conventional constraint-LDA approach, where all matrix elements of hybridization connecting the TM d orbitals and other orbitals are set to be zero. Then, we switch on the hybridization and evaluate the screening of on-site Coulomb interactions associated with the change of this hybridization in the random-phase approximation. The second channel of screening appears to be very important, and results in relatively small value of the effective Coulomb interaction for isolated t2g bands (about 2-3 eV, depending on the material). We discuss details of this screening and consider its band-filling dependence, frequency dependence, influence of the lattice distortion, proximity of other bands, as well as the effect of dimensionality of the model Hamiltonian. PACS numbers: 71.10.Fd; 71.15.Mb; 71.28.+d; 71.15.Ap In this paper we will discuss the first part of this project and show how results of conventional LDA calculations for the t 2g bands can be mapped onto the multi-orbital Hubbard model:
Full orbital calculation scheme for materials with strongly correlated electrons
Physical Review B, 2005
We propose a computational scheme for the ab initio calculation of Wannier functions (WFs) for correlated electronic materials. The full-orbital HamiltonianĤ is projected into the WF subspace defined by the physically most relevant partially filled bands. The HamiltonianĤ W F obtained in this way, with interaction parameters calculated by constrained LDA for the Wannier orbitals, is used as an ab initio setup of the correlation problem, which can then be solved by many-body techniques, e.g., dynamical mean-field theory (DMFT). In such calculations the self-energy operator Σ(ε) is defined in WF basis which then can be converted back into the full-orbital Hilbert space to compute the full-orbital interacting Green function G(r, r ′ , ε). Using G(r, r ′ , ε) one can evaluate the charge density, modified by correlations, together with a new set of WFs, thus defining a fully selfconsistent scheme. The Green function can also be used for the calculation of spectral, magnetic and electronic properties of the system. Here we report the results obtained with this method for SrVO 3 and V 2 O 3. Comparisons are made with previous results obtained by the LDA+DMFT approach where the LDA DOS was used as input, and with new bulk-sensitive experimental spectra.
arXiv (Cornell University), 2020
A central challenge in high throughput density functional theory (HT-DFT) calculations is selecting a combination of input parameters and post-processing techniques that can be used across all materials classes, while also managing accuracy-cost tradeoffs. To investigate the effects of these parameter choices, we consolidate three large HT-DFT databases: Automatic-FLOW (AFLOW), the Materials Project (MP), and the Open Quantum Materials Database (OQMD), and compare reported properties across each pair of databases for materials calculated using the same initial crystal structure. We find that HT-DFT formation energies and volumes are generally more reproducible than band gaps and total magnetizations; for instance, a notable fraction of records disagree on whether a material is metallic (up to 7%) or magnetic (up to 15%). The variance between calculated properties is as high as 0.105 eV/atom (median relative absolute difference, or MRAD, of 6%) for formation energy, 0.65 Å 3 /atom (MRAD of 4%) for volume, 0.21 eV (MRAD of 9%) for band gap, and 0.15 µB/formula unit (MRAD of 8%) for total magnetization, comparable to the differences between DFT and experiment. We trace some of the larger discrepancies to choices involving pseudopotentials, the DFT+U formalism, and elemental reference states, and argue that further standardization of HT-DFT would be beneficial to reproducibility.