Author
Oscar Grånäs
Other affiliations: Harvard University
Bio: Oscar Grånäs is an academic researcher from Uppsala University. The author has contributed to research in topics: Electronic structure & Density functional theory. The author has an hindex of 15, co-authored 44 publications receiving 1455 citations. Previous affiliations of Oscar Grånäs include Harvard University.
Papers
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Ghent University1, Forschungszentrum Jülich2, Åbo Akademi University3, Aalto University4, Vienna University of Technology5, Duke University6, University of Grenoble7, École Polytechnique Fédérale de Lausanne8, Durham University9, International School for Advanced Studies10, Max Planck Society11, Uppsala University12, Fritz Haber Institute of the Max Planck Society13, Humboldt University of Berlin14, Technical University of Denmark15, National Institute of Standards and Technology16, University of Udine17, Université catholique de Louvain18, University of Basel19, Harvard University20, University of California, Davis21, Rutgers University22, University of York23, Wake Forest University24, Science and Technology Facilities Council25, University of Oxford26, University of Vienna27, Leibniz Institute for Neurobiology28, Dresden University of Technology29, Radboud University Nijmegen30, University of Tokyo31, Centre national de la recherche scientifique32, University of Cambridge33, Royal Holloway, University of London34, University of California, Santa Barbara35, University of Luxembourg36, Los Alamos National Laboratory37, Harbin Institute of Technology38
TL;DR: A procedure to assess the precision of DFT methods was devised and used to demonstrate reproducibility among many of the most widely used DFT codes, demonstrating that the precisionof DFT implementations can be determined, even in the absence of one absolute reference code.
Abstract: The widespread popularity of density functional theory has given rise to an extensive range of dedicated codes for predicting molecular and crystalline properties. However, each code implements the formalism in a different way, raising questions about the reproducibility of such predictions. We report the results of a community-wide effort that compared 15 solid-state codes, using 40 different potentials or basis set types, to assess the quality of the Perdew-Burke-Ernzerhof equations of state for 71 elemental crystals. We conclude that predictions from recent codes and pseudopotentials agree very well, with pairwise differences that are comparable to those between different high-precision experiments. Older methods, however, have less precise agreement. Our benchmark provides a framework for users and developers to document the precision of new applications and methodological improvements.
1,141 citations
TL;DR: In this article, the effects of strong electron correlations are considered within the charge self-consistent density functional theory plus dynamical mean-field theory, and the exchange parameters are then extracted using the magnetic force theorem; hence all the calculations are performed within a single computational framework.
Abstract: In this paper we present an accurate numerical scheme for extracting interatomic exchange parameters (${J}_{ij}$) of strongly correlated systems, based on first-principles full-potential electronic structure theory. The electronic structure is modeled with the help of a full-potential linear muffin-tin orbital method. The effects of strong electron correlations are considered within the charge self-consistent density functional theory plus dynamical mean-field theory. The exchange parameters are then extracted using the magnetic force theorem; hence all the calculations are performed within a single computational framework. The method allows us to investigate how the ${J}_{ij}$ parameters are affected by dynamical electron correlations. In addition to describing the formalism and details of the implementation, we also present magnetic properties of a few commonly discussed systems, characterized by different degrees of electron localization. In bcc Fe, treated as a moderately correlated metal, we found a minor renormalization of the ${J}_{ij}$ interactions once the dynamical correlations are introduced. However, generally, if the magnetic coupling has several competing contributions from different orbitals, the redistribution of the spectral weight and changes in the exchange splitting of these states can lead to a dramatic modification of the total interaction parameter. In NiO we found that both static and dynamical mean-field results provide an adequate description of the exchange interactions, which is somewhat surprising given the fact that these two methods result in quite different electronic structures. By employing the Hubbard-I approximation for the treatment of the $4f$ states in hcp Gd we reproduce the experimentally observed multiplet structure. The calculated exchange parameters result in being rather close to the ones obtained by treating the $4f$ electrons as noninteracting core states.
80 citations
TL;DR: In this paper, full charge self-consistence (CSC) over the electron density has been implemented into the local density approximation plus dynamical mean field theory (LDA + DMFT) scheme based on a full-potential...
76 citations
TL;DR: Analysis and further calculations show that this type of multipole enters naturally in time reversal breaking in the presence of large effective spin-orbit coupling and coexists with magnetic moments for most magnetic actinides.
Abstract: A broken symmetry ground state without any magnetic moments has been calculated by means of the local-density approximation to density functional theory plus a local exchange term, the so-calle ...
70 citations
TL;DR: In this paper, a general reformulation of the exchange energy of $5f$ shell is applied in the analysis of the magnetic structure of various actinides compounds in the framework of the LDA+U$ method.
Abstract: A general reformulation of the exchange energy of $5f$ shell is applied in the analysis of the magnetic structure of various actinides compounds in the framework of $\text{LDA}+U$ method. The calculations are performed in a convenient scheme with essentially only one free parameter, the screening length. The results are analyzed in terms of different polarization channels due to different multipoles. Generally it is found that the spin-orbital polarization is dominating. This can be viewed as a strong enhancement of the spin-orbit coupling in these systems. This leads to a drastic decrease in spin polarization in accordance with experiments. The calculations are able to correctly differentiate magnetic and nonmagnetic Pu system. Finally, in all magnetic systems an unusual multipolar order is observed, whose polarization energy is often larger in magnitude than the one of spin polarization.
69 citations
Cited by
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University of Udine1, École Polytechnique Fédérale de Lausanne2, University of Lugano3, Leipzig University4, University of Paris5, University of North Texas6, Princeton University7, National Research Council8, International School for Advanced Studies9, Cornell University10, University of Lincoln11, University of Milan12, École Polytechnique13, International Centre for Theoretical Physics14, University of Paderborn15, University of Oxford16, Jožef Stefan Institute17, University of Padua18, Sapienza University of Rome19, Vietnam Academy of Science and Technology20, University of British Columbia21, Centre national de la recherche scientifique22, University of Lorraine23, University of Zurich24, École Normale Supérieure25, Université Paris-Saclay26, Wake Forest University27, Temple University28
TL;DR: Recent extensions and improvements are described, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.
Abstract: Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches Quantum ESPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement their ideas In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software
3,638 citations
University of Udine1, University of Lugano2, École Polytechnique Fédérale de Lausanne3, Leipzig University4, University of Paris5, University of North Texas6, Princeton University7, National Research Council8, International School for Advanced Studies9, Cornell University10, University of Lincoln11, University of Milan12, École Polytechnique13, International Centre for Theoretical Physics14, University of Paderborn15, University of Oxford16, Jožef Stefan Institute17, University of Padua18, Sapienza University of Rome19, Vietnam Academy of Science and Technology20, University of British Columbia21, University of Lorraine22, Centre national de la recherche scientifique23, University of Zurich24, École Normale Supérieure25, Université Paris-Saclay26, Wake Forest University27, Temple University28
TL;DR: Quantum ESPRESSO as discussed by the authors is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density functional theory, density functional perturbation theory, and many-body perturbations theory, within the plane-wave pseudo-potential and projector-augmented-wave approaches.
Abstract: Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudo-potential and projector-augmented-wave approaches. Quantum ESPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement theirs ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.
2,818 citations
TL;DR: A future in which the design, synthesis, characterization and application of molecules and materials is accelerated by artificial intelligence is envisaged.
Abstract: Here we summarize recent progress in machine learning for the chemical sciences. We outline machine-learning techniques that are suitable for addressing research questions in this domain, as well as future directions for the field. We envisage a future in which the design, synthesis, characterization and application of molecules and materials is accelerated by artificial intelligence.
2,295 citations
TL;DR: The largest available database of potentially exfoliable 2D materials has been obtained via high-throughput calculations using van der Waals density functional theory.
Abstract: Two-dimensional (2D) materials have emerged as promising candidates for next-generation electronic and optoelectronic applications. Yet, only a few dozen 2D materials have been successfully synthesized or exfoliated. Here, we search for 2D materials that can be easily exfoliated from their parent compounds. Starting from 108,423 unique, experimentally known 3D compounds, we identify a subset of 5,619 compounds that appear layered according to robust geometric and bonding criteria. High-throughput calculations using van der Waals density functional theory, validated against experimental structural data and calculated random phase approximation binding energies, further allowed the identification of 1,825 compounds that are either easily or potentially exfoliable. In particular, the subset of 1,036 easily exfoliable cases provides novel structural prototypes and simple ternary compounds as well as a large portfolio of materials to search from for optimal properties. For a subset of 258 compounds, we explore vibrational, electronic, magnetic and topological properties, identifying 56 ferromagnetic and antiferromagnetic systems, including half-metals and half-semiconductors.
1,336 citations