Modeling Magnetic Properties with Density Functional Theory‐Based Methods

Cirera, Jordi; Ruiz, Eliseo

doi:10.1002/9783527694228.ch17

Cited by 2 publications

(3 citation statements)

References 224 publications

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“…The ADF/BAND [81] code relies on a combination of NEGFs with a DFT description of the bulk contacts with the ability to break periodicity in one to three dimensions. Once placed between the electrodes, there is no control over the electronic structure of the molecule and the Green's functions are solved during a self-consistent transport calculation [113]. This is in contrast to codes like Gaussian [114], ADF [115], FHI-aims [116], or TURBOMOLE [117], in which the leads are treated as being finite and described within the quantum chemistry calculation.…”

Section: Methodsmentioning

confidence: 99%

First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials

et al. 2020

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One of the fundamental properties of semiconductors is their ability to support highly tunable electric currents in the presence of electric fields or carrier concentration gradients. These properties are described by transport coefficients such as electron and hole mobilities. Over the last decades, our understanding of carrier mobilities has largely been shaped by experimental investigations and empirical models. Recently, advances in electronic structure methods for real materials have made it possible to study these properties with predictive accuracy and without resorting to empirical parameters. These new developments are unlocking exciting new opportunities, from exploring carrier transport in quantum matter to in silico designing new semiconductors with tailored transport properties. In this article, we review the most recent developments in the area of ab initio calculations of carrier mobilities of semiconductors. Our aim is threefold: to make this rapidly-growing research area accessible to a broad community of condensed-matter theorists and materials scientists; to identify key challenges that need to be addressed in order to increase the predictive power of these methods; and to identify new opportunities for increasing the impact of these computational methods on the science and technology of advanced materials. The review is organized in three parts. In the first part, we offer a brief historical overview of approaches to the calculation of carrier mobilities, and we establish the conceptual framework underlying modern ab initio approaches. We summarize the Boltzmann theory of carrier transport and we discuss its scope of applicability, merits, and limitations in the broader context of many-body Green's function approaches. We discuss recent implementations of the Boltzmann formalism within the context of density functional theory and many-body perturbation theory calculations, placing an emphasis on the key computational challenges and suggested solutions. In the second part of the article, we review applications of these methods to materials of current interest, from three-dimensional semiconductors to layered and two-dimensional materials.In particular, we discuss in detail recent investigations of classic materials such as silicon, diamond, gallium arsenide, gallium nitride, gallium oxide, and lead halide perovskites as well as lowdimensional semiconductors such as graphene, silicene, phosphorene, molybdenum disulfide, and indium selenide. We also review recent efforts toward highthroughput calculations of carrier transport. In the last part, we identify important classes of materials for which an ab initio study of carrier mobilities arXiv:1908.01733v1 [cond-mat.mtrl-sci] 5 Aug 2019First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional mate is warranted. We discuss the extension of the methodology to study topological quantum matter and materials for spintronics and we comment on the possibility of incorporating Berry-phase effects ...

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Section: Methodsmentioning

confidence: 99%

First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials

et al. 2020

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“…Cluster complexes containing multiple magnetically coupled transition-metal ions have received intense and sustained attention from experiment and theory alike. − For example, oligonuclear systems of magnetically interacting manganese ions feature prominently in fields as diverse as single-molecule magnetism − and photosynthetic water oxidation. − A first-principles computational description of low-lying spin states in exchange-coupled transition-metal systems has been so far dominated by density functional theory with the broken-symmetry approach (BS-DFT). ,− The broken-symmetry solutions are not spin eigenstates and cannot be used directly for any comparisons with experiment, but the BS-DFT energies can be used to extract pairwise exchange coupling constants J ij to be substituted into an appropriate phenomenological Heisenberg–Dirac–van Vleck Hamiltonian (eq ). − …”

Section: Introductionmentioning

confidence: 99%

“…Although its practical utility is undeniable, the standard BS-DFT approach has weaknesses and shortcomings that relate to the formally deficient treatment of an intrinsically multireference problem, the dependence on the nature of the chemical system, and the sensitivity to the choice of density functional. ,− Other DFT-based approaches are being actively pursued. ,− Wave function based methods have been successfully employed only for a comparatively limited number of simple systems with few unpaired electrons. The use of multireference methods that address the static correlation problem, such as the complete active space self-consistent field (CASSCF), to directly obtain the energies of spin levels in magnetically coupled systems would be the most desirable foundation for tackling such problems, but their application is severely restricted by their computational cost.…”

Section: Introductionmentioning

confidence: 99%

Exchange Coupling Interactions from the Density Matrix Renormalization Group and N-Electron Valence Perturbation Theory: Application to a Biomimetic Mixed-Valence Manganese Complex

Roemelt

Krewald

Pantazis

2017

J. Chem. Theory Comput.

116

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The accurate description of magnetic level energetics in oligonuclear exchange-coupled transition-metal complexes remains a formidable challenge for quantum chemistry. The density matrix renormalization group (DMRG) brings such systems for the first time easily within reach of multireference wave function methods by enabling the use of unprecedentedly large active spaces. But does this guarantee systematic improvement in predictive ability and, if so, under which conditions? We identify operational parameters in the use of DMRG using as a test system an experimentally characterized mixed-valence bis-μ-oxo/μ-acetato Mn(III,IV) dimer, a model for the oxygen-evolving complex of photosystem II. A complete active space of all metal 3d and bridge 2p orbitals proved to be the smallest meaningful starting point; this is readily accessible with DMRG and greatly improves on the unrealistic metal-only configuration interaction or complete active space self-consistent field (CASSCF) values. Orbital optimization is critical for stabilizing the antiferromagnetic state, while a state-averaged approach over all spin states involved is required to avoid artificial deviations from isotropic behavior that are associated with state-specific calculations. Selective inclusion of localized orbital subspaces enables probing the relative contributions of different ligands and distinct superexchange pathways. Overall, however, full-valence DMRG-CASSCF calculations fall short of providing a quantitative description of the exchange coupling owing to insufficient recovery of dynamic correlation. Quantitatively accurate results can be achieved through a DMRG implementation of second order N-electron valence perturbation theory (NEVPT2) in conjunction with a full-valence metal and ligand active space. Perspectives for future applications of DMRG-CASSCF/NEVPT2 to exchange coupling in oligonuclear clusters are discussed.

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Modeling Magnetic Properties with Density Functional Theory‐Based Methods

Cited by 2 publications

References 224 publications

First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials

First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials

Exchange Coupling Interactions from the Density Matrix Renormalization Group and N-Electron Valence Perturbation Theory: Application to a Biomimetic Mixed-Valence Manganese Complex

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