Hynninen Antti-Pekka, Dijkstra Marjolein
Debye Institute, Soft Condensed Matter Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Aug;68(2 Pt 1):021407. doi: 10.1103/PhysRevE.68.021407. Epub 2003 Aug 19.
We determine the phase behavior of hard spheres interacting with repulsive Yukawa (screened Coulomb) interaction using computer simulations. We study the effect of the hard-core diameter on the phase behavior of repulsive Yukawa particles by comparing our phase diagrams with that of repulsive point Yukawa particles. We show that for sufficiently high contact values of the pair potential (betaepsilon=20, 39, 81, and higher), the fluid-face-centered-cubic (fcc) solid, at high screening, the fluid-body-centered-cubic (bcc) solid and the bcc-fcc coexistence for packing fractions eta less, similar 0.5 are well described by the phase boundaries of point Yukawa particles, by employing a mapping of the point Yukawa system onto a hard-core repulsive Yukawa system. While the bcc-fcc coexistence is well described by the point Yukawa limit for eta<0.5, we find a deviation at higher eta as the hard-core repulsion favors the fcc solid for eta>/=0.5, independent of the screening. Consequently, a second triple point appears in the phase diagram in the weak screening regime. In addition, we find that all the phase coexistence regions in our phase diagrams for hard-core repulsive Yukawa system are very narrow, i.e., a small density jump in the coexisting phases.
我们通过计算机模拟确定了与排斥性汤川（屏蔽库仑）相互作用的硬球的相行为。通过将我们的相图与排斥性点汤川粒子的相图进行比较，研究了硬核直径对排斥性汤川粒子相行为的影响。我们表明，对于足够高的对势接触值（βε = 20、39、81及更高），在高屏蔽下，流体面心立方（fcc）固体、流体体心立方（bcc）固体以及堆积分数η小于约0.5时的bcc - fcc共存情况，通过将点汤川系统映射到硬核排斥性汤川系统，能很好地由点汤川粒子的相边界来描述。虽然对于η < 0.5，bcc - fcc共存情况能很好地由点汤川极限描述，但我们发现，在较高的η时会出现偏差，因为对于η≥0.5，硬核排斥有利于fcc固体，且与屏蔽无关。因此，在弱屏蔽区域的相图中会出现第二个三相点。此外，我们发现，对于硬核排斥性汤川系统，我们相图中的所有相共存区域都非常窄，即在共存相中密度跳跃很小。
