Effect of Size Polydispersity on the Nature of Lennard-Jones Liquids
Effect of Size Polydispersity on the Nature of Lennard-Jones Liquids
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DOI：
10.1021/acs.jpcb.5b02329
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发表时间：
2015-08-27
影响因子：
3.3
通讯作者：
Tanaka, Hajime
中科院分区：
文献类型：
--
作者：
Ingebrigtsen, Trond S.;Tanaka, Hajime
多分散流体在生物和工业过程中随处可见。这些流体自然表现出丰富的现象学，表现出分馏和临界点和冻结温度的变化。我们在这里研究的Lennard-Jones（LJ）液体，这代表了大多数分子液体没有氢键，通过二维和三维分子动力学计算机模拟的基本性质上的大小多分散性的影响。已知由球形颗粒组成并通过LJ势相互作用的单组分液体在恒定体积下表现出维里和势能平衡波动之间的强相关性。这种相关性大大简化了液体的物理描述，这些液体现在被称为罗斯基勒简单（RS）液体。我们表明，这种简单的性质的单组分LJ液体被保存，即使是非常高的多分散性（超过40%的多分散性的研究均匀分布）。我们还研究适度多分散LJ液体的同构。同晶型物是指RS液体相图中的曲线，沿其沿着的结构、动力学和某些热力学量在无量纲单位下保持不变。我们发现，同构是一个很好的近似，即使是多分散LJ液体。因此，同晶理论很容易扩展到尺寸多分散流体，并可用于进一步提高这些有趣的系统的理解。
Polydisperse fluids are encountered everywhere in biological and industrial processes. These fluids naturally show a rich phenomenology exhibiting fractionation and shifts in critical point and freezing temperatures. We study here the effect of size polydispersity on the basic nature of Lennard-Jones (LJ) liquids, which represent most molecular liquids without hydrogen bonds, via two- and three-dimensional molecular dynamics computer simulations. A single-component liquid constituting spherical particles and interacting via the LJ potential is known to exhibit strong correlations between virial and potential energy equilibrium fluctuations at constant volume. This correlation significantly simplifies the physical description of the liquid, and these liquids are now known as Roskilde-simple (RS) liquids. We show that this simple nature of the single-component LJ liquid is preserved even for very high polydispersities (above 40% polydispersity for the studied uniform distribution). We also investigate isomorphs of moderately polydisperse LJ liquids. Isomorphs are curves in the phase diagram of RS liquids along which structure, dynamics, and some thermodynamic quantities are invariant in dimensionless units. We find that isomorphs are a good approximation even for polydisperse LJ liquids. The theory of isomorphs thus extends readily to size polydisperse fluids and can be used to improve even further the understanding of these intriguing systems.