Reduced partition function ratios of iron and oxygen in goethite

We present in full detail a newly developed formalism enabling density functional perturbation theory (DFPT) calculations from a DFT+U ground state. The implementation includes ultrasoft pseudopotentials and is valid for both insulating and metallic systems. It aims at fully exploiting the versatility of DFPT combined with the low-cost DFT+U functional. This allows to avoid computationally intensive frozen-phonon calculations when DFT+U is used to eliminate the residual electronic self-interaction from approximate functionals and to capture the localization of valence electrons e.g. on d or f states. In this way, the effects of electronic localization (possibly due to correlations) are consistently taken into account in the calculation of specific phonon modes, Born effective charges, dielectric tensors and in quantities requiring well converged sums over many phonon frequencies, as phonon density of states and free energies. The new computational tool is applied to two representative systems, namely CoO, a prototypical transition metal monoxide and LiCoO2, a material employed for the cathode of Li-ion batteries. The results show the effectiveness of our formalism to capture in a quantitatively reliable way the vibrational properties of systems with localized valence electrons. *

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“…The projections on the conduction manifold in Eq. (33) are conveniently rewritten using the definition in Eq. (26)…”

Section: A Response Hubbard Potential and Occupation Matrixmentioning

confidence: 99%

Hubbard-corrected density functional perturbation theory with ultrasoft pseudopotentials

et al. 2020

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“…This explains why, in the case of the hydroxylated oxygen atoms, Equation 11is not a valid approximation and meets the "correct" "-factor curve only at very high temperature whereas the approximation still holds for the other oxygen atoms. lines, unpublished data) are compared with the results given by Equation (10) using all vibrational frequencies (solid lines, Blanchard et al 2015).…”

Section: Approximate Formula Based On Force Constantsmentioning

confidence: 99%

“…In addition, the value of the scaling parameters may be associated with significant uncertainty, depending on the quality and precision of spectroscopic data available for the compound of interest. Some studies that focus on crystals choose to correct the theoretical results by fixing the unit cell parameters to the experimental values and by optimizing only the atomic positions (e.g., Kowalski and Jahn 2011;Blanchard et al 2015;Pinilla et al 2015), but this procedure will usually not completely correct systematic errors in the electronic structure method, and it will of course not be applicable in materials where unit cell parameters are not known a priori.…”

Section: Quantum-mechanical Molecular Modelingmentioning

confidence: 99%

“…-Iron: Several DFT studies focused on isotopic fractionation among Fe species in aqueous solution (Anbar et al 2005;Domagal-Goldman and Kubicki 2008;Hill and Schauble 2008;Zuccolini 2008, 2009;Hill et al 2010;Fujii et al 2014), others looked at iron-bearing minerals such as hematite, goethite, pyrite and siderite (Blanchard et al 2009(Blanchard et al , 2010(Blanchard et al , 2015. Rustad and Yin (2009) investigated the isotopic properties of ferropericlase and ferroperovskite in lower-mantle conditions to discuss the Earth accretion and differentiation.…”

Section: Theoretical Studies Of Non-traditional Stable Isotope Fractimentioning

confidence: 99%

“…#$! address this issue, Dauphas and collaborators have developed a software (SciPhon) that reliably corrects for non-constant baseline (Dauphas et al 2014;Blanchard et al 2015;Roskosz et al 2015). .…”

Section: Mössbauer and Nrixs Spectroscopymentioning

confidence: 99%

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