Berlin 2018 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 53: Complex Fluids and Soft Matter (joint session DY/ CPP / BP)

DY 53.7: Talk

Wednesday, March 14, 2018, 17:15–17:30, BH-N 334

Phasonic equilibrium in colloidal quasicrystals — •Johannes Hielscher and Sebastian C. Kapfer — FAU Erlangen-Nürnberg, Institut für Theoretische Physik

We study decagonal intrinsic quasicrystals in two dimensions that are supported by a short-range double-minimum pair potential. Spatial correlations of phasonic flips [1], the preference of rational approximants at low temperatures [2], and energetic considerations indicate that a mathematically ideal quasicrystal is not an equilibrium state of this system.

We conduct Monte Carlo simulations of phasonic flips, using a model potential that separates configurational (phasonic) contributions from the influence of continuous (phononic) displacements. Amplitude and extent of collective phasonic excitations depend on temperature, hence also the frequencies of local motifs.

The isolation of the phasonic degrees of freedom enables a separate inspection of thermodynamic properties of these excitations, such as the heat capacity. We discuss how to translate these findings into the thermodynamics of systems governed by physical dynamics.

[1] J. Hielscher, M. Martinsons, M. Schmiedeberg & S. C. Kapfer: J. Phys.: Cond. Matt. 29, 094002 (2017)

[2] A. Kiselev, M. Engel & H.-R. Trebin, Phys. Rev. Lett. 109, 225502 (2012)