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

• Published in: arXiv.org
• Main Authors: Gabriëlse, Alexander, Löwen, Hartmut, Smallenburg, Frank
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 03.11.2017
• Subjects: Algorithms; Computer simulation; Crystal lattices; Crystal structure; Monte Carlo simulation; Nanoparticles; Phase diagrams; Physics - Soft Condensed Matter
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1711.01103

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.