Title: On the stress overshoot in cluster crystals under shear
Author(s):

	G.P. Shrivastav (Institut für Theoretische Physik and Center for Computational Materials Science (CMS), TU Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria),
	G. Kahl (Institut für Theoretische Physik and Center for Computational Materials Science (CMS), TU Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria)

Using non-equilibrium molecular dynamics simulations we study the yielding behaviour of a model cluster crystal formed by ultrasoft particles under shear. We investigate the evolution of stress as a function of strain for different shear rates, , and temperatures. The stress-strain relation displays a pronounced maximum at the yielding point; the height of this maximum, σ_p, increases via a power law with an increasing shear range and tends to saturate to a finite value if the limit shear rate goes to zero (at least within the considered temperature range). Interestingly, this behaviour can be captured by the Herschel-Bulkley type model which, for a given temperature, allows us to predict a static yield stress σ_p⁰ (in the shear rate tending to zero limit), a characteristic timescale τ_c, and the exponent α of the above-mentioned power-law decay of the σ_p at high shear rates. Furthermore, for different temperatures, the σ_p can be scaled as functions of onto a single master curve when scaled by corresponding τ_c and σ_p⁰. Moreover, for a given shear rate, σ_p displays a logarithmic dependence on temperature. Again, the σ_p–T curves for different shear rates can be scaled on a single logarithmic master curve when scaled by a corresponding fitting parameters.

Key words: rheology, cluster crystals, yielding, molecular dynamics, stress overshoot

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