SPAM - Science, Pizza And Mathematics

26.01.2026
 

A Unified Approach to Defects in Crystals and Quasicrystals

Abstract: Defects play a central role in determining the mechanical and structural properties of crystalline and quasicrystalline materials, yet modeling their dynamics across scales remains challenging. The phase-field crystal (PFC) model offers a powerful mesoscale approach by retaining atomic-scale information while evolving on diffusive time scales. Its amplitude expansion (APFC) further enables efficient large-scale simulations, but has traditionally been limited to a small set of lattice symmetries. In this talk, we develop a generalized amplitude-based framework that extends APFC to a wide range of crystal structures, including non-Bravais lattices. The formulation preserves computational efficiency while accurately capturing elasticity and defect networks, as demonstrated for systems such as hexagonal close-packed and diamond lattices. We also extend the amplitude approach to quasicrystals, constructing a mesoscale model that naturally incorporates both phonon and phason degrees of freedom. Without prescribing defects explicitly, the framework predicts the emergence of dislocations, semi-coherent interfaces, and complex defect patterns under strain.

Vortragender: Marcello De Donno

TBA

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30.01.2020