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arXiv 1004.1064cond-mat.softphysics.chem-ph
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斑块大小和数目对斑块胶体简单模型的影响

Effects of patch size and number within a simple model of patchy colloids

Achille Giacometti, Fred Lado, Julio Largo, Giorgio Pastore, Francesco Sciortino

摘要:

我们报告的计算机模拟和积分方程研究的一个简单的模型的补丁球,每个表面装饰有两个相反的吸引力帽,作为一个功能的分数$χ$覆盖的吸引表面。探讨的简单模型-两块Kern-Frenkel模型-在改变覆盖范围$χ$的情况下在方阱和硬球势之间插值。我们发现,积分方程理论提供了定量预测在整个探索区域的温度和密度从方井极限$χ= 1.0$到$χ\approx 0.6$。对于较小的$χ$,良好的数值收敛的方程,只有在温度大于气液临界点,然而,积分方程理论提供了一个完整的描述的角度依赖性。这些结果进行了对比与那些为一个补丁的情况下。我们通过数值模拟研究了剩余的覆盖区域,并显示了气-液临界点如何随着$χ$的减小而向更小的密度和温度移动。在$χ\approx 0.3$以下,结晶阻止了观察临界点线演变的可能性,提供了在降低球势范围时液体作为平衡相消失的角度模拟。最后,我们表明,稳定有序相的演变减少$χ$从一个三维晶体的互连平面到一个二维的独立平面结构的链的一维流体时,每个补丁的一个键的限制,最终达到。

英文摘要:

We report on a computer simulation and integral equation study of a simple model of patchy spheres, each of whose surfaces is decorated with two opposite attractive caps, as a function of the fraction $χ$ of covered attractive surface. The simple model explored --- the two-patch Kern-Frenkel model --- interpolates between a square-well and a hard-sphere potential on changing the coverage $χ$. We show that integral equation theory provides quantitative predictions in the entire explored region of temperatures and densities from the square-well limit $χ= 1.0$ down to $χ\approx 0.6$. For smaller $χ$, good numerical convergence of the equations is achieved only at temperatures larger than the gas-liquid critical point, where however integral equation theory provides a complete description of the angular dependence. These results are contrasted with those for the one-patch case. We investigate the remaining region of coverage via numerical simulation and show how the gas-liquid critical point moves to smaller densities and temperatures on decreasing $χ$. Below $χ\approx 0.3$, crystallization prevents the possibility of observing the evolution of the line of critical points, providing the angular analog of the disappearance of the liquid as an equilibrium phase on decreasing the range for spherical potentials. Finally, we show that the stable ordered phase evolves on decreasing $χ$ from a three-dimensional crystal of interconnected planes to a two-dimensional independent-planes structure to a one-dimensional fluid of chains when the one-bond-per-patch limit is eventually reached.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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