Zero temperature phase diagram of the square-shoulder system

被引:61
作者
Pauschenwein, Gernot J. [1 ]
Kahl, Gerhard
机构
[1] Vienna Univ Technol, Inst Theoret Phys, A-1040 Vienna, Austria
关键词
aggregates (materials); free energy; genetic algorithms; high-pressure solid-state phase transformations; phase diagrams;
D O I
10.1063/1.3006065
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Particles that interact via a square-shoulder potential, consisting of an impenetrable hard core with an adjacent, repulsive, steplike corona, are able to self-organize in a surprisingly rich variety of rather unconventional ordered, three-dimensional structures. Using optimization strategies that are based on ideas of genetic algorithms, we encounter, as we systematically increase the pressure, the following archetypes of aggregates: low-symmetry cluster and columnar phases, followed by lamellar particle arrangements, until at high pressure values compact, high-symmetry lattices emerge. These structures are characterized in the isobaric-isothermal ensemble as configurations of minimum Gibbs free energy. Based on simple considerations, i.e., basically minimizing the number of overlapping coronas while maximizing at the same time the density, the sequence of emerging structures can easily be understood. In contrast to a previous contribution [G. J. Pauschenwein and G. Kahl, Soft Matter 4, 1396 (2008)], we present here a systematic investigation of this phenomenon, considering a short, an intermediate, and a large shoulder width.
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页数:12
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