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Weck, Philippe F.; Kim, Eunja; Greathouse, Jeffery A.; Gordon, Margaret Ellen; Bryan, Charles R.

doi:10.1016/j.cplett.2018.03.025

Cited by 9 publications

(25 citation statements)

References 28 publications

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“…However, for the case of rutherfordine and gamma uranium trioxide phases, the specialized version of PBE functional for solid materials, PBEsol [127], provided much better results [99,100,121]. The improved description of the structure of properties of anhydrous materials using this functional over the one obtained using PBE was observed in recent calculations [99,100,121] and later confirmed by other research groups [128,129]. This justifies the great amount of effort made in developing density functionals specific for solid materials [130] and emphasizes the need of determining empirical dispersion parameters specific for these functionals.…”

Section: Computational Methodologymentioning

confidence: 66%

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

Ruiz¹

2019

Density Functional Theory

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With the advent of increased computer capacities, improved computational resources, and easier access to large-scale computer facilities, the use of density functional theory methods has become nowadays a frequently used and highly successful approach for the research of solid-state materials. However, the study of solid materials containing heavy elements as lanthanide and actinide elements is very complex due to the large size of these atoms and the requirement of including relativistic effects. These features impose the availability of large computational resources and the use of high quality relativistic pseudopotentials for the description of the electrons localized in the inner shells of these atoms. The important case of the description of uranyl-containing materials and their properties has been faced recently. The study of these materials is very important in the energetic and environmental disciplines. Uranyl-containing materials are fundamental components of the paragenetic sequence of secondary phases that results from the weathering of uraninite ore deposits and are also prominent phases appearing from the alteration of the spent nuclear fuel. The development of a new norm-conserving relativistic pseudopotential for uranium, the use of energy density functionals specific for solids, and the inclusion of empirical dispersion corrections for describing the long-range interactions present in the structures of these materials have allowed the study of the properties of these materials with an unprecedented accuracy level. This feature is very relevant because these methods provide a safe, accurate, and cheap manner of obtaining these properties for uranium-containing materials which are highly radiotoxic, and their experimental studies demand a careful handling of the samples used. In this work, the results of recent applications of theoretical solid state methods based on density functional theory using plane waves and pseudopotentials to the determination of the thermodynamic properties and stability of uranyl-containing materials are reviewed. The knowledge of these thermodynamic properties is indispensable to model the dynamical behavior of nuclear materials under diverse geochemical conditions. The theoretical methods provide

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Section: Computational Methodologymentioning

confidence: 66%

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

Ruiz¹

2019

Density Functional Theory

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“…Both functionals were found in previous studies to correctly describe the geometric parameters and properties of a variety of Zr compounds and oxides. [38][39][40][46][47][48] Properties such as the thermodynamic ones previously calculated with PBEsol for non-NTE materials and oxides showed overall improvement compared with PBE results. [47,49,50] PBEsol elasticity and thermodynamics calculations for α-ZrW 2 O 8 also exhibit better agreement with experiments than other functionals.…”

Section: Methodsmentioning

confidence: 83%

“…Properties such as the thermodynamic ones previously calculated with PBEsol for non‐NTE materials and oxides showed overall improvement compared with PBE results . PBEsol elasticity and thermodynamics calculations for α‐ZrW 2 O 8 also exhibit better agreement with experiments than other functionals …”

Section: Methodsmentioning

confidence: 99%

“…[47,49,50] PBEsol elasticity and thermodynamics calculations for α-ZrW 2 O 8 also exhibit better agreement with experiments than other functionals. [48] The interaction between valence electrons and ionic cores was described by the projector-augmented wave method. [51,52] The Zr(4p 6 ,5s 2 ,4d 2 ), W(6s 2 ,5d 4 ), and O(2s 2 ,2p 4 ) electrons were treated explicitly as valence electrons in the Kohn-Sham equations, and the remaining core electrons together with the nuclei were represented by projector-augmented wave pseudopotentials.…”

Section: Methodsmentioning

confidence: 99%

“…This DFPT approach was utilized in previous computational studies to successfully predict the properties of various Zr-containing compounds and crystalline materials. [38][39][40][41]46,48,49,[55][56][57] 3 | RESULTS AND DISCUSSION…”

Section: Methodsmentioning

confidence: 99%

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Infrared and Raman spectroscopy of α‐ZrW₂O₈: A comprehensive density functional perturbation theory and experimental study

Weck

Gordon

Greathouse

et al. 2018

J Raman Spectroscopy

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Cubic zirconium tungstate (α‐ZrW2O8), a well‐known negative thermal expansion material, has been investigated within the framework of density functional perturbation theory (DFPT), combined with experimental characterization to assess and validate computational results. Using combined Fourier transform infrared measurements and DFPT calculations, new and extensive assignments were made for the far‐infrared (<400 cm−1) spectrum of α‐ZrW2O8. A systematic comparison of DFPT‐simulated infrared, Raman, and phonon density‐of‐state spectra with Fourier transform far‐/mid‐infrared and Raman data collected in this study, as well as with available inelastic neutron scattering measurements, shows the superior accuracy of the PBEsol exchange‐correlation functional over standard PBE calculations for studying the spectroscopic properties of this material.

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Understanding the Origin of the Particularly Small and Anisotropic Thermal Expansion of MOF‐74

Kamencek

Schrode

Resel

et al. 2022

Advcd Theory and Sims

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Metal-organic frameworks often display large positive or negative thermal expansion coefficients. MOF-74, a material envisioned for many applications, shows a different behavior. Temperature-dependent X-ray diffraction reveals particularly small negative (positive) thermal expansion coefficients perpendicular (parallel) to the hexagonally arranged pores. These trends are explained by combining density-functional theory calculations with the Grüneisen theory of thermal expansion, which allows tracing back thermal expansion to contributions of individual phonons. On the macroscopic level, the small thermal expansion coefficients arise from compensation effects caused by the large coupling between perpendicular stress and strain and by the small magnitudes of the mean Grüneisen tensor elements, 〈𝜸〉. These provide information on how strains impact phonon frequencies. To understand the small value of 〈𝜸〉, the individual mode contributions are analyzed using the corresponding atomic motions. This reveals that only the lowest frequency modes up to ≈3 THz provide non-negligible contributions, such that 〈𝜸〉 drops sharply at higher temperatures. These considerations reveal, how the details of the anharmonic properties of specific phonon bands determine the magnitude and sign of thermal expansion in a prototypical material like MOF-74. Beyond that, the authors also discuss, how the choice of the theoretical methodology impacts the obtained results.

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Assessing exchange-correlation functionals for elasticity and thermodynamics of α-ZrW2O8

Cited by 9 publications

References 28 publications

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

Infrared and Raman spectroscopy of α‐ZrW₂O₈: A comprehensive density functional perturbation theory and experimental study

Understanding the Origin of the Particularly Small and Anisotropic Thermal Expansion of MOF‐74

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Assessing exchange-correlation functionals for elasticity and thermodynamics of α-ZrW2O8

Cited by 9 publications

References 28 publications

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

The Application of Periodic Density Functional Theory to the Study of Uranyl-Containing Materials: Thermodynamic Properties and Stability

Infrared and Raman spectroscopy of α‐ZrW2O8: A comprehensive density functional perturbation theory and experimental study

Understanding the Origin of the Particularly Small and Anisotropic Thermal Expansion of MOF‐74

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Infrared and Raman spectroscopy of α‐ZrW₂O₈: A comprehensive density functional perturbation theory and experimental study