Efficient systematic scheme to construct second-principles lattice-dynamical models
| Autor: | Carlos Escorihuela-Sayalero, Jorge Íñiguez, Jacek C. Wojdeł |
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| Rok vydání: | 2016 |
| Předmět: |
Condensed Matter - Materials Science
Phase transition Training set Computer science Phonon Diagonalizable matrix Anharmonicity Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Bounded function Lattice (order) 0103 physical sciences Statistical physics 010306 general physics 0210 nano-technology |
| DOI: | 10.48550/arxiv.1608.06788 |
| Popis: | We start from the polynomic interatomic potentials introduced by Wojde{\l} et al. [J. Phys. Condens. Matt. 25, 305401(2013)] and take advantage of one of their key features -- namely, the linear dependence of the energy on the potential's adjustable parameters -- to devise a scheme for the construction of first-principles-based ({\em second-principles}) models for large-scale lattice-dynamical simulations. Our method presents the following convenient features. The parameters of the model are computed in a very fast and efficient way, as it is possible to recast the fit to a training set of first-principles data into a simple matrix diagonalization problem. Our method selects automatically the interactions that are most relevant to reproduce the training-set data, by choosing from a pool that includes virtually all possible coupling terms, and produces a family of models of increasing complexity and accuracy. We work with practical and convenient cross-validation criteria linked to the physical properties that will be relevant in future simulations based on the new model, and which greatly facilitate the task of identifying a potential that is simultaneously simple (thus computationally light), very accurate, and predictive. We also discuss practical ways to guarantee that our energy models are bounded from below, with a minimal impact on their accuracy. Finally, we demonstrate our scheme with an application to ferroelastic perovskite SrTiO$_{3}$, which features many non-trivial lattice-dynamical features (e.g., a phase transition driven by soft phonons, competing structural instabilities, highly anharmonic dynamics) and provides a very demanding test. Comment: 22 pages, 13 figures |
| Databáze: | OpenAIRE |
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