Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 31: Topical session (Symposium MM): Fundamentals of Fracture

MM 31.1: Topical Talk

Mittwoch, 14. März 2018, 10:15–10:45, TC 006

Multiscale QM/MM Modelling of Materials Chemomechanics — •James Kermode — Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry, UK

Fracture is the dominant failure process underlying many materials reliability issues. At the same time, it remains one of the most challenging multi-scale modelling problems, requiring both an accurate description of the chemical processes occurring in the near tip region and the inclusion of a much larger region in the model systems. These requirements can be met simultaneously by combining a quantum mechanical description of the crack tip with a classical atomistic model that captures the long-range elastic behaviour of the surrounding crystal matrix, using a QM/MM (quantum mechanics/molecular mechanics) approach such as the `Learn on the Fly* (LOTF) scheme [1]. I will review recent applications of this scheme to slow crack growth [2] and chemically activated fracture [3], and discuss a recent extension to the approach that uses the principle of virtual work with a modified nudged elastic band (NEB) algorithm to compute energy barriers for activated processes within the QM/MM framework [5]. The new method has been applied to compute lattice trapping barriers to brittle fracture in silicon as well and dislocation migration barriers in molybdenum and tungsten.

[1] G. Csányi et al., Phys. Rev. Lett. 93, 175503 (2004); [2] J. R. Kermode et al., Phys. Rev. Lett. 115, 135501 (2015); [3] A. Gleizer et al., Phys. Rev. Lett. 112, 115501 (2014); [5] T. Swinburne and J.R. Kermode, Phys. Rev. B 96, 144102 (2017)