Sampling vacancy configurations with large relaxations using Smart Darting

Döme Tanguy (1)

1 ILM - Institut Lumière Matière [Villeurbanne]

Markov chain Monte Carlo simulations, combining the sampling of the position of the particles and their chemical nature, are very useful when calculating, for example, average site occupancies at crystalline defects in alloys. Unfortunately, when the relaxations around the solutes are large, the exchange moves can be systematically rejected because of atoms overlapping. As a consequence, the simulations are often trapped in nonphysical configurations. In this paper, the "Smart Darting" method from Andricioaei et al. is adapted and extended to propose a solution to this limitation. The method is tested in a particularly demanding case: the sampling of the arrangements of delocalized vacancies and divacancies in grain boundaries, both in the fcc and the bcc structure. Beyond the methodological aspects, intergranular vacancy clusters are interesting in several contexts such as ductile fracture, irradiation or thin film dewetting, and therefore several properties have been measured that can be useful for mesoscale modeling: segregation energies, effective diffusion barriers in and out of the grain boundaries, vacancy-vacancy binding energies and elastic dipole tensors.

Domaines: Physique [physics]

Döme Tanguy. Sampling vacancy configurations with large relaxations using Smart Darting. Physical Review Materials, 2024, 8 (3), pp.033604. ⟨10.1103/PhysRevMaterials.8.033604⟩. ⟨hal-04245426v2⟩