Vacancy-stabilized crystalline order in hard cubes.

Smallenburg, Frank; Filion, Laura; Marechal, Matthieu; Dijkstra, Marjolein · Proc Natl Acad Sci U S A · 2012

basic_science · Level V

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Abstract

We examine the effect of vacancies on the phase behavior and structure of systems consisting of hard cubes using event-driven molecular dynamics and Monte Carlo simulations. We find a first-order phase transition between a fluid and a simple cubic crystal phase that is stabilized by a surprisingly large number of vacancies, reaching a net vacancy concentration of approximately 6.4% near bulk coexistence. Remarkably, we find that vacancies increase the positional order in the system. Finally, we show that the vacancies are delocalized and therefore hard to detect.