Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 31: Computational Materials Modelling: Physics of Ensembles 2
MM 31.4: Talk
Thursday, September 8, 2022, 12:30–12:45, H44
Approximating nuclear quantum effects in solids by temperature remapping — •Raynol Dsouza1, Liam Huber1, Blazej Grabowski2, and Jörg Neugebauer1 — 1Max Planck Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany — 2University of Stuttgart, 70569 Stuttgart, Germany
The quantum nature of solids, which is especially important at low temperatures, is often ignored in finite temperature atomistic simulations. Formulations to estimate quantum anharmonic effects precisely, such as the path integral method, are computationally demanding. Although various acceleration approaches allowing quantum effects to be fully accounted for in systems of hundreds of atoms have been proposed over the last two decades, they can fall short when it comes to modeling defects in solids, which can require significantly larger system sizes. We present a new approach for approximating nuclear quantum effects, exploiting a temperature map between the quantum system and its best classical surrogate. This map is constructed using the internal energies of classical and quantum harmonic oscillators within the Debye model. To a good approximation, our approach captures the impact of quantum effects on lattice constants, internal energies, and heat capacities with almost no additional cost compared to purely classical molecular dynamics simulations. Results for diamond cubic carbon and silicon are in good agreement with available literature values, which use full path integral Monte-Carlo simulations. We also show how this approach can be used to predict phase transition temperatures, e.g. the FCC to BCC transition for calcium.