Berlin 2018 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 71: Methods in Computational Materials Modelling (methodological aspects, numerics)
MM 71.2: Vortrag
Freitag, 16. März 2018, 09:45–10:00, TC 006
First-principles calculations of lattice-vacancy diffusion coefficients via non equilibrium ab initio molecular dynamics — •Igor A. Abrikosov1,2, Davide G. Sangiovanni1,3, Davide Gambino1, and Björn Alling1,4 — 1Linköping University, Sweden — 2National University of Science and Technology "MISIS", Moscow, Russia — 3Ruhr-Universität Bochum, Germany — 4Max-Planck-Institut für Eisenforschung GmbH, Germany
We revisit the color-diffusion (CD) algorithm in non equilibrium ab initio molecular dynamics (NE-AIMD) and propose substantially more efficient approach for the estimation of monovacancy jump rates in crystalline solids at temperatures well below melting [1]. Considering bcc Mo between 1000 and 2800 K as a model system, NE-AIMD results show that the colored-atom jump rate increases exponentially with the force intensity F, up to F values far beyond the linear-fitting regime employed previously. At the same time, equilibrium rates extrapolated by NE-AIMD results are in excellent agreement with those of unconstrained dynamics. The gain in computational efficiency increases rapidly with decreasing temperatures and reaches a factor of 4 orders of magnitude at the lowest temperature considered in the present study. Moreover, we demonstrate the applicability of the CD algorithm in simulations of Ti monovacancy jump frequencies in a compound, NaCl-structure titanium nitride (TiN), at temperatures ranging from 2200 to 3000 K [2].
[1] D. G. Sangiovanni, et al., Phys. Rev. B 93, 094305 (2016).
[2] D. Gambino, et al., Phys. Rev. B 96, 104306 (2017).