Fasolo Moreno, Sollich Peter
Department of Mathematics, King's College London, London WC2R 2LS, United Kingdom.
Phys Rev Lett. 2003 Aug 8;91(6):068301. doi: 10.1103/PhysRevLett.91.068301.
We calculate the phase behavior of hard spheres with size polydispersity, using accurate free energies for the fluid and solid phases. Cloud and shadow curves are found exactly by the moment free energy method, but we also compute the complete phase diagram, taking full account of fractionation. In contrast to earlier, simplified treatments we find no point of equal concentration between fluid and solid or reentrant melting at higher densities. Rather, the fluid cloud curve continues to the largest polydispersity that we study (14%); from the equilibrium phase behavior a terminal polydispersity can thus be defined only for the solid, where we find it to be around 7%. At sufficiently large polydispersity, fractionation into several solid phases can occur, consistent with previous approximate calculations; we find, in addition, that coexistence of several solids with a fluid phase is also possible.
我们使用流体相和固相的精确自由能来计算具有尺寸多分散性的硬球的相行为。通过矩自由能方法精确地找到了云线和阴影曲线，但我们也计算了完整的相图，充分考虑了分馏现象。与早期的简化处理不同，我们发现在流体和固体之间不存在等浓度点，在更高密度下也不存在再入熔化现象。相反，流体云线延伸到我们所研究的最大多分散性（14%）；因此，从平衡相行为来看，只能为固体定义一个终端多分散性，我们发现其约为7%。在足够大的多分散性下，可能会分馏成几个固相，这与之前的近似计算一致；此外，我们还发现几种固体与流体相共存也是可能的。
