Effect of three-body interactions on the phase behavior of charge-stabilized colloidal suspensions.
Effect of three-body interactions on the phase behavior of charge-stabilized colloidal suspensions.
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DOI：
10.1103/physreve.69.061407
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发表时间：
2004-06
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影响因子：
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通讯作者：
Antti-Pekka Hynninen;M. Dijkstra;R. V. Roij
中科院分区：
文献类型：
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作者：
Antti-Pekka Hynninen;M. Dijkstra;R. V. Roij
数值研究了三重吸引相互作用对低盐度下高电荷胶体颗粒悬浮液相行为的影响。在我们的计算机模拟中，我们采用从数值泊松-玻尔兹曼研究[物理评论E 66，011402（2002）]中获得的对和三重态势。在自由能计算的基础上，我们确定了直径sigma=32 nm、电荷Z=80的相同球体的水悬浮液的相图作为胶体浓度和盐度的函数，无论是对于纯成对添加剂系统还是对于具有对和三重态相互作用的系统。包括三重态相互作用的主要效果是有利于面心立方（fcc）晶相的体心立方（bcc）晶相的不稳定。因此，相图的特点是在低盐度下，相当稀的流体与几乎紧密堆积的fcc相共存，而在中等盐度下，bcc-fcc共存，具有较大的密度跳跃。在足够高的盐度下，三重吸引力不影响相行为;在这些条件下，系统很好地描述了成对电位。
We study numerically the effect of attractive triplet interactions on the phase behavior of suspensions of highly charged colloidal particles at low salinity. In our computer simulations, we employ the pair and triplet potentials that were obtained from a numerical Poisson-Boltzmann study [Phys. Rev. E 66, 011402 (2002)]]. On the basis of free energy calculations, we determine the phase diagram of an aqueous suspension of identical spheres of diameter sigma=32 nm and charge Z=80 as a function of colloid concentration and salinity, both for the purely pairwise additive system and for the system with pair and triplet interactions. The main effect of including the triplet interactions is a destabilization of the body-centered-cubic (bcc) crystal phase in favor of the face-centered-cubic (fcc) crystal phase. As a consequence the phase diagram features the coexistence of a rather dilute fluid with an almost-close-packed fcc phase at low salinity and bcc-fcc coexistence with a big density jump at intermediate salinity. The triplet attractions do not affect the phase behavior at sufficiently high salinity; under these conditions the system is well described by the pairwise potential.