Development of Density-Functional Tight-Binding Parameters for the Molecular Dynamics Simulation of Zirconia, Yttria, and Yttria-Stabilized Zirconia

Abstract

In this work, a set of density-functional tight-binding (DFTB) parameters for the Zr−Zr, Zr−O, Y−Y, Y−O, and Zr− Y interactions was developed for bulk and surface simulations of ZrO 2 (zirconia), Y 2 O 3 (yttria), and yttria-stabilized zirconia (YSZ) materials. The parameterization lays the ground work for realistic simulations of zirconia-, yttria-, and YSZ-based electrolytes in solid oxide fuel cells and YSZ-based catalysts on long timescales and relevant size scales. The parameterization was validated for the zirconia and yttria polymorphs observed under standard conditions based on density functional theory calculations and experimental data. Additionally, we performed DFTB-based molecular dynamics (MD) simulations to compute structural and vibrationalproperties of these materials. The results show that the parameters can give a qualitatively correct phase ordering of zirconia, where the tetragonal phase is more stable than the cubic phase at a lower temperature. The lattice parameters are only slightly overestimated by 0.05−0.1 Å (2% error), still within the typical accuracy of first-principles methods. Additionally, the MD results confirm that zirconia and yttria phases are stable against transformations under standard conditions. The parameterization also predicts that vibrational spectra are within the range of 100−1000 cm −1 for zirconia and 100−800 cm −1 for yttria, which is in good agreement with predictions both from full quantum mechanics and a recently developed classical force field. To further demonstrate the advantage of the developed DFTB parameters in terms of computational resources, we conducted DFTB/MD simulations of the YSZ4 and YS12 models containing approximately 750 atoms.

Density Functional Theory Study of the Spin–Orbit Insulating Phase in SnTe Cubic Nanowires: Implications for Topological Electronics

“…To improve the present results within DFT accuracy, one of the few possible options is to move to the density functional-based tight binding method, which is based on a second-order expansion of the Kohn–Sham total energy with respect to charge density fluctuations. 62 In order to investigate Majorana fermions, the SnTe NWs should host superconductivity beyond the topological properties demonstrated in the previous section. The superconductivity can be realized using the proximity effect 63 by doping 64 or interfacing SnTe with PbTe.…”

Toward Understanding and Controlling Organic Reactions on Metal Oxide Catalysts

“…Lower panel: transition state of aldol addition through an X + −Enolate ∧ Keto mechanism over a reduced surface of CeO 2 (111), where an aldehyde and enolate each adsorbed at surface oxygen vacancy sites. molecular dynamics, 102 these simulation methods as well as kinetic Monte Carlo 103 methods will enable a more full understanding of what occurs on any given surface under a given set of conditions. Conclusions about the dominant reactive adsorbate species must be carefully interpreted to be condition dependent.…”

“…The age-old geometric vs electronic arguments tend to persist with this chemistry, and our abilities to identify the true underlying nature of the proposed chemistry are rapidly advancing with improved characterization and theory. As machine learning augmented electronic structure calculations increase in accuracy and advances are made in ab initio molecular dynamics, these simulation methods as well as kinetic Monte Carlo methods will enable a more full understanding of what occurs on any given surface under a given set of conditions. Conclusions about the dominant reactive adsorbate species must be carefully interpreted to be condition dependent.…”

Prediction of induced magnetism in 2D Ti2C based MXenes by manipulating the mixed surface functionalization and metal substitution computed by xTB model Hamiltonian of the DFTB method

“…14,44,45 The applicability of the DFTB method requires the availability of parameter sets for all pairs of atoms present in the system. 46,47 This approach has been already tested on the 2D materials 48 and it was applied for defected Ti 2 CO 2 MXene. 14 However, when compared with the exact eigenstates and eigenvalues from the exact calculations in the finite Hubbard model, 49 the tight binding case is a rather crude approximation.…”