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 paper, the trends in CO adsorption on close-packed metal surfaces were studied using density functional theory, and the effect of specific changes in the setup such as choice of the exchange correlation functional, the choice of pseudopotential and size of the basis set, substrate relaxation has been carefully evaluated.
Abstract: We have studied the trends in CO adsorption on close-packed metal surfaces: Co, Ni, Cu from the 3d row, Ru, Rh, Pd, Ag from the 4d row and Ir, Pt, Au from the 5d row using density functional theory. In particular, we were concerned with the trends in the adsorption energy, the geometry, the vibrational properties and other parameters derived from the electronic structure of the substrate. The influence of specific changes in our setup such as choice of the exchange correlation functional, the choice of pseudopotential and size of the basis set, substrate relaxation has been carefully evaluated. We found that while the geometrical and vibrational properties of the adsorbate-substrate complex are calculated with high accuracy, the adsorption energies calculated with the gradient-corrected Perdew-Wang exchange-correlation energies are overestimated. In addition, the calculations tend to favour adsorption sites with higher coordination, resulting in the prediction of wrong adsorption sites for the Rh, Pt and Cu surfaces (hollow instead of top). The revised Perdew-Burke-Erzernhof functional (RPBE) leads to lower (i.e. more realistic) adsorption energies for transition metals, but to wrong results for noble metals - for Ag and Au endothermic adsorption is predicted. The site preference remains the same. We discuss trends in relation to the electronic structure of the substrate across the Periodic Table, summarizing the state-of-the-art of CO adsorption on close-packed metal surfaces.
354 citations
TL;DR: In this paper, the dependence on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the multiferroic material bismuth ferrite was investigated using first principles density functional theory calculations.
Abstract: The dependencies on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the multiferroic material bismuth ferrite, $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$, are investigated using first principles density functional theory calculations. The electric polarization is found to be rather independent of strain, in striking contrast to most conventional perovskite ferroelectrics. It is also not significantly affected by oxygen vacancies, or by the combined presence of strain and oxygen vacancies. The magnetization is also unaffected by strain, however, the incorporation of oxygen vacancies can alter the magnetization slightly, and also leads to the formation of ${\mathrm{Fe}}^{2+}$. These results are discussed in light of recent experiments on epitaxial films of $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$, which reported a strong thickness dependence of both magnetization and polarization.
353 citations
TL;DR: In this article, the spinless nodal fermion semimetal phase in ZrSiS was established using angle-resolved photoemission spectroscopy and first-principles calculations.
Abstract: The search for new topological phases of matter is a major new direction in condensed matter physics. Recent experimental realizations of Dirac and Weyl semimetal phases pave the way to look for other exotic phases of matter in real materials. In this paper, the authors present a systematic angle-resolved photoemission spectroscopy study of ZrSiS, a potential topological nodal semimetal candidate. Their systematic measurements establish the spinless nodal fermion semimetal phase in ZrSiS, which is supported by their first-principles calculations. This work puts forward the ZrSiS-type material family as a new platform to explore exotic states of quantum matter.
352 citations
University of Cambridge1, Imperial College London2, Cornell University3, South Ural State University4, University College London5, University of Amsterdam6, University of Bologna7, Indian Institute of Science8, Utrecht University9, University of Buenos Aires10, University of Erlangen-Nuremberg11, Ruhr University Bochum12, University of Bradford13, University of Utah14
TL;DR: The results of the fifth blind test of crystal structure prediction, which show important success with more challenging large and flexible molecules, are presented and discussed.
Abstract: Following on from the success of the previous crystal structure prediction blind tests (CSP1999, CSP2001, CSP2004 and CSP2007), a fifth such collaborative project (CSP2010) was organized at the Cambridge Crystallographic Data Centre. A range of methodologies was used by the participating groups in order to evaluate the ability of the current computational methods to predict the crystal structures of the six organic molecules chosen as targets for this blind test. The first four targets, two rigid molecules, one semi-flexible molecule and a 1:1 salt, matched the criteria for the targets from CSP2007, while the last two targets belonged to two new challenging categories – a larger, much more flexible molecule and a hydrate with more than one polymorph. Each group submitted three predictions for each target it attempted. There was at least one successful prediction for each target, and two groups were able to successfully predict the structure of the large flexible molecule as their first place submission. The results show that while not as many groups successfully predicted the structures of the three smallest molecules as in CSP2007, there is now evidence that methodologies such as dispersion-corrected density functional theory (DFT-D) are able to reliably do so. The results also highlight the many challenges posed by more complex systems and show that there are still issues to be overcome.
352 citations
Cites background from "From ultrasoft pseudopotentials to ..."
...…(2005), Pickard & Needs (2006), Pickard & Needs (2011); (k) Neumann & Perrin (2005), Neumann (2008, 2011), Kresse & Furthmüller (1996), Kresse & Hafner (1993), Kresse & Joubert (1999); (l) Gavezzotti (2003), Gavezzotti & Filippini (1997), Gavezzotti (2002); (m) Karamertzanis & Pantelides…...
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01 Aug 2020
TL;DR: In this paper, the reactive facets of polytriazine imides (PTIs) intercalated with LiCl and achieved a remarkable improvement in its overall photocatalytic water splitting activity.
Abstract: Unraveling how reactive facets promote photocatalysis at the molecular level remains a grand challenge, while identification of the reactive facets can provide guidelines for designing highly efficient photocatalysts and unravelling the microscopic mechanisms behind them Recently, a series of polytriazine imides (PTIs) was reported with highly crystalline structures; all had a relatively low photocatalytic activity for overall water splitting Here, high-angle annular dark-field scanning transmission electron microscopy, energy dispersive spectroscopy mapping, and aberration-corrected integrated differential phase contrast imaging were used to study PTI/Li+Cl− single crystals before and after in situ photodeposition of co-catalysts, showing that the prismatic {10
$$\bar 1$$
0} planes are more photocatalytically reactive than the basal {0001} planes Theoretical calculations confirmed that the electrons are energetically favourable to transfer toward the {10
$$\bar 1$$
0} planes Upon this discovery, PTI/Li+Cl− crystals with different aspect ratios were prepared, and the overall water splitting performance followed a linear correlation with the relative surface areas of the {10
$$\bar 1$$
0} and {0001} planes Our controlling of the reactive facets directly instructs the development of highly efficient polymer photocatalysts for overall water splitting Unlike with inorganic photocatalysts, the facet-dependent reactivity of conjugated polymers remains elusive Now, the authors provide molecular-level insights on the reactive facets of crystalline poly(triazine imide) intercalated with LiCl and achieve a remarkable improvement in its overall photocatalytic water splitting activity
351 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