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HL: Fachverband Halbleiterphysik
HL 40: Thermal, acoustic and transport properties
HL 40.2: Vortrag
Mittwoch, 18. März 2020, 09:45–10:00, POT 151
Optimized internal-coordinates Gartstein potential for graphene, boron nitride and their nanotubes — •Francesco Libbi1, Nicola Bonini2, and Nicola Marzari1,3 — 1Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland — 2Physics Department, King's College, London, United Kingdom — 3National Centre for Computational Design and Discovery of Novel Materials (MARVEL)
The lattice dynamics and, in particular, the quadratic behaviour of the flexural acoustic modes in low-dimensional materials play a fundamental role in their thermo-mechanical and thermal transport properties. A first-principles evaluation of these properties can be computationally very demanding and can be affected by numerical errors which break translational or rotational invariance. In order to overcome these problems in graphene-like materials, we develop an internal-coordinate potential with 13 parameters tuned on first-principles phonon calculations. We show that the potential not only reproduces very well the phonon dispersion of graphene, but that the same potential also describes correctly the vibrational properties of carbon nanotubes of arbitrary diameter and chirality. In addition, it is very easy to modify it adding a cubic term to reproduce the dominant anharmonic force constants. This allows a good estimate of lattice thermal conductivities. The potential form works well also for other 2D honeycomb lattice materials, including the case of hexagonal, polar, boron nitride.