On-the-fly parameterization of internal coordinate force constants for quasi-Newton geometry optimization in atomistic calculations

Freysoldt, Christoph

doi:10.1016/j.commatsci.2017.03.001

Cited by 8 publications

(4 citation statements)

References 31 publications

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“…For structural relaxations, the "external structure optimizer" (SxExtOpt) [51] is used for the following reasons: (i) Since the average of forces is performed outside the DFT code, a structure optimizer independent of the potential energy surface calculation is required. (ii) SxExtOpt shows a very fast convergence to the structure of lowest energy as it models the Hessian based on internal coordinates and parametrizes it on the fly.…”

Section: G Simulation Protocolmentioning

confidence: 99%

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

et al. 2020

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Lattice and magnetic degrees of freedom are strongly coupled in magnetic materials. We propose a consistent first-principles framework to explore the joint configurational space. For this, we define atomic spin moments from the projector augmented-wave formalism of density-functional theory and control them via Lagrangian constraints. We demonstrate our approach for vacancy formation and migration in collinear paramagnetic bcc iron by implementing a relaxation scheme based on spin-space averaged forces (SSA relaxation). Based on these results we discuss the impact of the magnetic state on vacancy formation energies, migration barriers, and relaxations.

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Section: G Simulation Protocolmentioning

confidence: 99%

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

et al. 2020

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“…The interactions are determined from a least-square fit of the forces from more than 1500 configurations of an MD run at 3000 K at the target lattice constant. Owing to the harmonic approximation, the fitting problem is linear [49] and is solved with a standard algebraic method, namely the pseudo-inverse from singular value decomposition to avoid accidental ill-conditioning. The zero-force reference structure, where the potential attains its minimum is set to the 0 K equilibrium geometry.…”

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confidence: 99%

Ab initio vibrational free energies including anharmonicity for multicomponent alloys

et al. 2019

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A density-functional-theory based approach to efficiently compute numerically exact vibrational free energies-including anharmonicity-for chemically complex multicomponent alloys is developed. It is based on a combination of thermodynamic integration and a machine-learning potential. We demonstrate the performance of the approach by computing the anharmonic free energy of the prototypical five-component VNbMoTaW refractory high entropy alloy. arXiv:1902.11230v1 [cond-mat.mtrl-sci]

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“…This precision leads to accurate force calculations and stable convergence behaviour, ensuring reliability without erratic outcomes. In conclusion, BFGS's optimization efficiency, global capabilities, curvature incorporation, and smooth convergence greatly enhance Cartesian force calculation accuracy [45,46].…”

Section: Te Parameters and Optimization Calculationsmentioning

confidence: 96%

Thermoelectric optimization using first principles calculation and single parabolic band model: a case of Ca_0.5La_0.5−xBi _x MnO₃ (x = 0, 0.25)

Raharjo,

Kurniawan,

Soegijono

et al. 2024

Modelling Simul. Mater. Sci. Eng.

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Conducting optimization calculations for thermoelectric performance can be beneficial in guiding the direction of further experimental work. In our study, we utilize a combination of the first principle, Boltzmann transport and restructured single parabolic band model to investigate the half-doped semiconductors based on manganite. Ca0.5La0.5-xBixMnO3 (x = 0, 0.25) as samples shows the power factor (PF) optimum value of 30% and 69% for x = 0 and 0.25, respectively at a temperature of 800 K. In addition, both samples show two to three orders of magnitude smaller lattice thermal conductivity than their electronic thermal conductivity. This excludes complex phononic transport mechanisms from the calculation of the figure of merit (ZT). The ZT calculations of CLMO and CLBMO are corrected by the ratio of the transport relaxation time of electrical conductivity to the transport relaxation time of electronic thermal conductivity by the Lorenz number, resulting in ZT values of 0.063 and 0.327 at a temperature of 800 K, respectively.

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On-the-fly parameterization of internal coordinate force constants for quasi-Newton geometry optimization in atomistic calculations

Cited by 8 publications

References 31 publications

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Ab initio vibrational free energies including anharmonicity for multicomponent alloys

Thermoelectric optimization using first principles calculation and single parabolic band model: a case of Ca_0.5La_0.5−xBi _x MnO₃ (x = 0, 0.25)

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On-the-fly parameterization of internal coordinate force constants for quasi-Newton geometry optimization in atomistic calculations

Cited by 8 publications

References 31 publications

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Ab initio vibrational free energies including anharmonicity for multicomponent alloys

Thermoelectric optimization using first principles calculation and single parabolic band model: a case of Ca0.5La0.5−x Bi x MnO3 (x = 0, 0.25)

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Thermoelectric optimization using first principles calculation and single parabolic band model: a case of Ca_0.5La_0.5−xBi _x MnO₃ (x = 0, 0.25)