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arXiv 1908.10622cond-mat.softcond-mat.stat-mech
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液-气不对称条件下流体界面区关联式的微观确定

Microscopic determination of correlations in the fluid interfacial region in the presence of liquid-gas asymmetry

Andrew O. Parry, Carlos Rascón

摘要:

在最近的一篇文章中,我们展示了在具有短程力的系统中,如何通过考虑局部结构因子[Nat.Phys.~]的共振,在微观上理解流体界面区域中的密度-密度关联函数及其积分,即局部结构因子的性质。{ \bf 15},287(2019)]。在这里,我们说明,使用平均场平方梯度理论和更微观的沙利文密度泛函模型,这种方法如何推广时,有液-气不对称,即当共存的液相和气相的体积相关长度是不同的。特别是,我们能够表示的关联函数\textit{exactly}作为一个简单的平均值的贡献所产生的两个有效的伊辛对称系统称为对称气体和对称液体。当与我们以前的结果相结合,这产生的关联函数和局部结构因子,这是近难以区分的数值解的Ornstein-Zernike方程在整个范围内的波矢量的解析近似。我们的研究结果突出了不对称性如何影响的关联函数结构,并描述了从一个长期的戈德斯通模式的本地密度确定的短期属性的交叉,作为波矢量的增加。

英文摘要:

In a recent article, we showed how the properties of the density-density correlation function and its integral, the local structure factor, in the fluid interfacial region, in systems with short-ranged forces, can be understood microscopically by considering the resonances of the local structure factor [Nat.Phys.~{\bf 15}, 287 (2019)]. Here we illustrate, using mean-field square-gradient theory and the more microscopic Sullivan density functional model, how this approach generalises when there is liquid-gas asymmetry, i.e. when the bulk correlation lengths of the coexisting liquid and gas phases are different. In particular, we are able to express the correlation function \textit{exactly} as a simple average of contributions arising from two effective Ising-symmetric systems referred to as the symmetric gas and symmetric liquid. When combined with our earlier results, this generates analytical approximations for the correlation function and the local structure factor, which are near indistinguishable from the numerical solution to the Ornstein-Zernike equations over the whole range of wave-vectors. Our results highlight how asymmetry affects the correlation function structure, and describes the crossover from a long-ranged Goldstone mode to short-ranged properties determined by the local density, as the wave-vector increases.

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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