Langevin dynamics simulations of a two-dimensional colloidal crystal under confinement and shear

D. Wilms, P. Virnau, S. Sengupta, and K. Binder
Phys. Rev. E 85, 061406 – Published 18 June 2012

Abstract

Langevin dynamics simulations are used to study the effect of shear on a two-dimensional colloidal crystal (with implicit solvent) confined by structured parallel walls. When walls are sheared very slowly, only two or three crystalline layers next to the walls move along with them, while the inner layers of the crystal are only slightly tilted. At higher shear velocities, this inner part of the crystal breaks into several pieces with different orientations. The velocity profile across the slit is reminiscent of shear banding in flowing soft materials, where liquid and solid regions coexist; the difference, however, is that in the latter case the solid regions are glassy while here they are crystalline. At even higher shear velocities, the effect of the shearing becomes smaller again. Also the effective temperature near the walls (deduced from the velocity distributions of the particles) decreases again when the wall velocity gets very large. When the walls are placed closer together, thereby introducing an incommensurability between the periodicity of the confined crystal and the walls, a structure containing a soliton staircase arises in simulations without shear. Introducing shear increases the disorder in these systems until no solitons are visible anymore. Instead, similar structures like in the case without mismatch result. At high shear rates, configurations where the incommensurability of the crystalline structure is compensated by the creation of holes become relevant.

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  • Received 16 March 2012

DOI:https://doi.org/10.1103/PhysRevE.85.061406

©2012 American Physical Society

Authors & Affiliations

D. Wilms1,2, P. Virnau1, S. Sengupta3,4, and K. Binder1

  • 1Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
  • 2Graduate School Materials Science in Mainz, Staudinger Weg 9, D-55128 Mainz, Germany
  • 3Indian Association for the Cultivation of Science, Centre for Advanced Materials, Jadavpur, Kolkata 700032, India
  • 4Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Gandipet Road, Narsingi, Hyderabad 500075, India

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Issue

Vol. 85, Iss. 6 — June 2012

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