Low-temperature crystal structures of the hard core square shoulder model

Alexander Gabriëlse; Hartmut Löwen; Frank Smallenburg

doi:10.3390/ma10111280

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arXiv · 1711.01103

Low-temperature crystal structures of the hard core square shoulder model

Alexander Gabriëlse·Hartmut Löwen·Frank Smallenburg

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Abstract

In many cases, the stability of complex structures in colloidal systems is enhanced by a competition between different length scales. Inspired by recent experiments on nanoparticles coated with polymers, we use Monte Carlo simulations to explore the types of crystal structures that can form in a simple hard-core square shoulder model which explicitly incorporates two favored distances between the particles. To this end, we combine Monte Carlo-based crystal structure finding algorithms with free energies obtained using a mean-field cell theory approach, and draw phase diagrams for two different values of the square shoulder width as a function of the density and temperature. Moreover, we map out the zero-temperature phase diagram for a broad range of shoulder widths. Our results show the stability of a rich variety of crystal phases, such as body-centered orthogonal (BCO) lattices, not previously considered for the square shoulder model.

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Alexander Gabriëlse, Hartmut Löwen, Frank Smallenburg. 2017-11-03. Low-temperature crystal structures of the hard core square shoulder model. https://doi.org/10.3390/ma10111280

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