Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 28: Focus Session: Heat transport at the nanoscale: theory meets experiment

HL 28.9: Talk

Wednesday, March 20, 2024, 12:45–13:00, EW 203

Quantitatively accurate description of heat transport in metal-organic frameworks — Sandro Wieser, Florian Lindner, Lukas Legenstein, Lukas Reicht, and •Egbert Zojer — Institute of Solid State Physics, Graz University of Technology, Graz, Austria

Metal-organic frameworks (MOFs) comprise a highly porous class of materials consisting of metal-oxide nodes and organic linkers. They are envisioned for a wide variety of applications, many of which involve the generation or consumption of thermal energy. Therefore, understanding their heat-transport properties is of crucial importance. Unfortunately, MOFs are typically so complex (containing dozens or even hundreds of atoms in their unit cells), that an ab initio-based simulation of thermal transport appears impossible. Also conventional, transferable force fields are not suitable for the task, as they yield thermal conductivity values far from experiments. In the current contribution we show that the situation can be resolved employing on-the-fly-trained, machine-learned potentials (MLPs), which enable an essentially ab initio-quality description of phonon properties of MOFs at computational costs reduced by many orders of magnitude. Interestingly, with accurate MLPs at hand, various applied methodologies (NEMD, AEMD, Green-Kubo MD, as well as lattice dynamics) yield equivalent results in quantitative agreement with experimental, single crystal data. A similar situation is encountered for polymers and molecular crystals. The results pave the way for a reliable, atomistic understanding of heat transport in the said materials.

Keywords: heat transport; molecular dynamics; machine-learned potential; metal-organic framework