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Journal ArticleDOI

From ultrasoft pseudopotentials to the projector augmented-wave method

15 Jan 1999-Physical Review B (American Physical Society)-Vol. 59, Iss: 3, pp 1758-1775
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.
Citations
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Posted Content
TL;DR: The projector augmented wave (PAW) method as mentioned in this paper is an all-electron method for efficient ab-initio molecular dynamics simulations with the full wave functions, which extends and combines the traditions of existing augmented wave methods and the pseudopotential approach.
Abstract: A brief introduction to the projector augmented wave method is given and recent developments are reviewed. The projector augmented wave method is an all-electron method for efficient ab-initio molecular dynamics simulations with the full wave functions. It extends and combines the traditions of existing augmented wave methods and the pseudopotential approach. Without sacrificing efficiency, the PAW method avoids transferability problems of the pseudopotential approach and it has been valuable to predict properties that depend on the full wave functions.

275 citations


Cites background or methods from "From ultrasoft pseudopotentials to ..."

  • ...As shown by Watson and Carter (1998) and Kresse and Joubert (1999) most pseudopotentials fail for high spin atoms such as Cr....

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  • ...Recently the PAW method has been implemented into the VASP code (Kresse and Joubert 1999)....

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  • ...The implementation by Kresse and Joubert (1999) has been particularly useful as they had an implementation of PAW in the same code as the ultra-soft pseudopotentials, so that they could critically compare the two approaches with each other and LAPW calculations....

    [...]

Journal ArticleDOI
TL;DR: Using operando X-ray diffraction, it is shown that oxidation of electrochemically generated Li2O2 occurs in two stages, but in one step for bulk crystalline (commercial) Li2 O2, revealing a fundamental difference in the OER process depending on the nature of the peroxide.
Abstract: Fundamental research into the Li–O2 battery system has gone into high gear, gaining momentum because of its very high theoretical specific energy. Much progress has been made toward understanding the discharge mechanism, but the mechanism of the oxygen evolution reaction (OER) on charge (i.e., oxidation) remains less understood. Here, using operando X-ray diffraction, we show that oxidation of electrochemically generated Li2O2 occurs in two stages, but in one step for bulk crystalline (commercial) Li2O2, revealing a fundamental difference in the OER process depending on the nature of the peroxide. For electrochemically generated Li2O2, oxidation proceeds first through a noncrystalline lithium peroxide component, followed at higher potential by the crystalline peroxide via a Li deficient solid solution (Li2–xO2) phase. Anisotropic broadening of the X-ray Li2O2 reflections confirms a platelet crystallite shape. On the basis of the evolution of the broadening during charge, we speculate that the toroid parti...

275 citations

Journal ArticleDOI
01 Jan 2021-ChemRxiv
TL;DR: In this paper, it was shown that Fe-N-C catalysts initially comprising two distinct FeNx sites (S1 and S2) degrade via the transformation of S1 into iron oxides while the structure and number of S2 were unmodified.
Abstract: While Fe-N-C materials are a promising alternative to platinum for catalyzing oxygen reduction in acidic polymer fuel cells, limited understanding of their operando degradation restricts rational approaches towards improved durability. Here we show that Fe-N-C catalysts initially comprising two distinct FeNx sites (S1 and S2) degrade via the transformation of S1 into iron oxides while the structure and number of S2 were unmodified. Structure-activity correlations drawn from end-of-test 57Fe Mossbauer spectroscopy reveal that both sites initially contribute to the ORR activity but only S2 significantly contributes after 50 h of operation. From in situ 57Fe Mossbauer spectroscopy in inert gas coupled to calculations of the Mossbauer signature of FeNx moieties in different electronic states, we identify S1 to be a high-spin FeN4C12 moiety and S2 a low- or intermediate spin FeN4C10 moiety. These insights lay the ground for rational approaches towards Fe-N-C cathodes with improved durability in acidic fuel cells.

274 citations

Journal ArticleDOI
TL;DR: The larger EA of BiOI also results in a reduced overpotential for O2/oxygen anion splitting and can explain why BiOi is not as active for the degradation of rhodamine B than BiOBr and BiOCl.
Abstract: The optoelectronic properties of bismuth oxyhalides have led to their utility in applications such as pigments in the cosmetics industry,1,2 pharmaceuticals,3,4 phosphors,5 gas sensors,6 and catalysis.7,8 Over the past decade, interest in this family of materials has rapidly increased, fuelled by reports of their excellent photocatalytic activity.9−16 They have been studied as stand-alone photocatalysts,9,10,17 quaternary alloys,18,19 and interfaced with other photocatalytically active materials.20−22 To date, however, an understanding of the chemical trends underpinning these successes is lacking.

274 citations

Journal ArticleDOI
18 May 2015-Nature
TL;DR: In this article, coherent optical excitation of molecular vibrations in the organic conductor K3C60 can induce a non-equilibrium state with the optical properties of a superconductor, and a transient gap in the real part of the optical conductivity and a low-frequency divergence of the imaginary part are measured for base temperatures far above equilibrium Tc=20 K.
Abstract: The control of non-equilibrium phenomena in complex solids is an important research frontier, encompassing new effects like light induced superconductivity. Here, we show that coherent optical excitation of molecular vibrations in the organic conductor K3C60 can induce a non-equilibrium state with the optical properties of a superconductor. A transient gap in the real part of the optical conductivity and a low-frequency divergence of the imaginary part are measured for base temperatures far above equilibrium Tc=20 K. These findings underscore the role of coherent light fields in inducing emergent order.

274 citations

References
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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