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PGI-1 Talk: Dr. Rico Friedrich

Computational Materials Thermodynamics

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18 Dec 2018 11:30
venue
PGI Lecture Hall

Duke University, Durham, USA

Abstract:

The Automatic-Flow for Materials Discovery (AFLOW) database and software provides a platform for leveraging ab initio calculations for computational materials design – critically relying on the accurate prediction of thermodynamic properties.

As a first example, the creation of spontaneously forming, i.e. thermodynamically driven, superlattices of topological insulators is addressed. Spinodal decomposition – a controllable kinetic phenomenon – is proposed as a natural design strategy for superlattices of TlBiX2 (X=S, Se, Te) systems. The resulting band structures show various features such as topological interface states, spin texture gain by nontopological states, band inversion and Rashba-like states.

The accurate calculation of formation enthalpies – quantifying the thermodynamic stability of a compound – is crucial for computational materials design. For several classes of systems such as oxides, standard semi-local functionals suffer from a lack of error cancellation leading to deviations of several hundred meV/atom compared to experimental values. We propose the “coordination-corrected-enthalpies” method (CCE), which is also capable of correcting the relative stability of polymorphs.

The approach uses calculations employing the PBE, LDA and SCAN exchange correlation functionals, in conjunction with a quasiharmonic Debye model to treat zero-point vibrational and thermal effects. The scheme predicts very accurate room temperature results for all functionals, with the smallest mean absolute error of 27 meV/atom obtained with SCAN. Zero-point vibrational and thermal contributions to the formation enthalpy are found to largely cancel each other.

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de

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