From ultrasoft pseudopotentials to the projector augmented-wave method
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Abstract: The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Bl\"ochl's projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addition, critical tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed core all electron methods. These tests include small molecules $({\mathrm{H}}_{2}{,\mathrm{}\mathrm{H}}_{2}{\mathrm{O},\mathrm{}\mathrm{Li}}_{2}{,\mathrm{}\mathrm{N}}_{2}{,\mathrm{}\mathrm{F}}_{2}{,\mathrm{}\mathrm{BF}}_{3}{,\mathrm{}\mathrm{SiF}}_{4})$ and several bulk systems (diamond, Si, V, Li, Ca, ${\mathrm{CaF}}_{2},$ Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.
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TL;DR: In this article, the authors demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites (Au-1/FeOx) are much more sinteringresistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range.
Abstract: Supported noble metal nanoparticles (including nanoclusters) are widely used in many industrial catalytic processes While the finely dispersed nanostructures are highly active, they are usually thermodynamically unstable and tend to aggregate or sinter at elevated temperatures This scenario is particularly true for supported nanogold catalysts because the gold nanostructures are easily sintered at high temperatures, under reaction conditions, or even during storage at ambient temperature Here, we demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites (Au-1/FeOx) are much more sinteringresistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range Theoretical studies revealed that the positively charged and surface-anchored Au1 atoms with high valent states formed significant covalent metal-support interactions (CMSIs), thus providing the ultra-stability and remarkable catalytic performance This work may provide insights and a new avenue for fabricating supported Au catalysts with ultra-high stability
390 citations
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...2).[41] A cluster model was also used to determine the charge distribution and the possible formal oxidation states of Au1 embedded on the support surface....
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TL;DR: In this article, the performance of the dispersion correction D3 with and without an explicit three-body dispersion term for the energetic and structural properties of rare gas and molecular crystals is investigated.
Abstract: We investigate the performance of the dispersion correction D3 with and without an explicit three-body dispersion term for the energetic and structural properties of rare gas and molecular crystals. Therefore, the two- and three-body gradient of the dispersion energy is implemented in the periodic plane-wave program VASP. It is combined with different density functionals at the level of the general gradient approximation (GGA) and hybrid functionals. Cohesive energies and lattice parameters for the rare gas crystals Ar, Kr, and Xe and a set of 23 molecular crystals are calculated and compared to experimental reference values. In general, all tested methods yield very good results. For the molecular crystals the mean absolute deviation of lattice energies from reference data (about 1–2 kcal/mol) is close to or below their uncertainties. The influence of the three-body Axilrod–Teller–Muto dispersion term on energy and structure is found to be rather small. While on a GGA level cohesive energies become sligh...
389 citations
TL;DR: In this article, the authors developed a computationally efficient model where the electrode part of the interface is described at the density-functional theory (DFT) level, and the electrolyte part is represented through an implicit solvation model based on the Poisson-Boltzmann equation.
Abstract: The ab initio computational treatment of electrochemical systems requires an appropriate treatment of the solid/liquid interfaces. A fully quantum mechanical treatment of the interface is computationally demanding due to the large number of degrees of freedom involved. In this work, we develop a computationally efficient model where the electrode part of the interface is described at the density-functional theory (DFT) level, and the electrolyte part is represented through an implicit solvation model based on the Poisson-Boltzmann equation. We describe the implementation of the linearized Poisson-Boltzmann equation into the Vienna Ab initio Simulation Package, a widely used DFT code, followed by validation and benchmarking of the method. To demonstrate the utility of the implicit electrolyte model, we apply it to study the surface energy of Cu crystal facets in an aqueous electrolyte as a function of applied electric potential. We show that the applied potential enables the control of the shape of nanocrystals from an octahedral to a truncated octahedral morphology with increasing potential.
388 citations
TL;DR: In this paper, density functional theory (DFT) is used to reveal that the polycrystalline Young's modulus (E) of graphite triples as it is lithiated to LiC 6 is captured in a linear relationship between E and lithium concentration suitable for predicting diffusion-induced deformation in battery electrode materials.
Abstract: Density functional theory (DFT) is used to reveal that the polycrystalline Young's modulus (E) of graphite triples as it is lithiated to LiC 6 This behavior is captured in a linear relationship between E and lithium concentration suitable for continuum-scale models aimed at predicting diffusion-induced deformation in battery electrode materials Alternatively, Poisson's ratio is concentration-independent Charge-transfer analyses suggest simultaneous weakening of carbon-carbon bonds within graphite basal planes and strengthening of interlayer bonding during lithiation The variation in bond strength is shown to be responsible for the differences between elasticity tensor components, C ij , of lithium-graphite intercalation (Li-GIC) phases Strain accumulation during Li intercalation and deintercalation is examined with a core-shell model of a Li-GIC particle assuming two coexisting phases The requisite force equilibrium uses different Young's moduli computed with DFT Lithium-poor phases develop tensile strains, whereas Li-rich phases develop compressive strains Results from the core-shell model suggest that elastic strain should be defined relative to the newest phase that forms during lithiation of graphite, and Li concentration-dependent mechanical properties should be considered in continuum level models
387 citations
TL;DR: In this paper, a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for high-conductivity LLZO compositions based on Al and Ta doping.
Abstract: The oxide known as LLZO, with nominal composition Li7La3Zr2O12, is a promising solid electrolyte for Li-based batteries due to its high Li-ion conductivity and chemical stability with respect to lithium. Solid electrolytes may also enable the use of metallic Li anodes by serving as a physical barrier that suppresses dendrite initiation and propagation during cycling. Prior linear elasticity models of the Li electrode/solid electrolyte interface suggest that the stability of this interface is highly dependent on the elastic properties of the solid separator. For example, dendritic suppression is predicted to be enhanced as the electrolyte’s shear modulus increases. In the present study a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for high-conductivity LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good agreement and fall ...
387 citations
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Book•
31 Dec 1993
TL;DR: The linearized augmented planewave (LAPW) method has emerged as the standard by which density functional calculations for transition metal and rare-earth containing materials are judged.
Abstract: With its extreme accuracy and reasonable computational efficiency, the linearized augmented planewave (LAPW) method has emerged as the standard by which density functional calculations for transition metal and rare-earth containing materials are judged. This volume presents a thorough and self-conta
1,150 citations