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arXiv 1208.3089cond-mat.softcond-mat.stat-mechphysics.chem-ph
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硬球混合物的相容基本测度自由能类

Class of consistent fundamental-measure free energies for hard-sphere mixtures

Andrés Santos

摘要:

在基本测度理论中,硬球流体混合物的体积过剩自由能量密度被假定为仅通过四个标度粒子理论变量${ξ_α}$取决于部分数密度${ρ_i}$,即,$Φ({ρ_i})\toΦ({ξ_α})$。通过施加一致性条件,在此证明了这样的相关性必须具有$Φ({ξ_α})=-ξ_0\ln(1-ξ_3)+Ψ(y)ξ_1ξ_2/(1-ξ_3)$的形式,其中$y\equiv {ξ_2^2}/{12πξ_1 (1-ξ_3)}$是标度变量,而$Ψ(y)$是可以从单组分体系的自由能量密度确定的任意无量纲标度函数。扩展到非齐次的情况下,实现了由基本措施(标量,矢量和张量)加权密度${n_α(\mathbf{r})}$的变量${ξ_α}$的标准替代。与计算机模拟的比较表明,这种体自由能优于白熊之一。

英文摘要:

In fundamental-measure theories the bulk excess free-energy density of a hard-sphere fluid mixture is assumed to depend on the partial number densities ${ρ_i}$ only through the four scaled-particle-theory variables ${ξ_α}$, i.e., $Φ({ρ_i})\toΦ({ξ_α})$. By imposing consistency conditions, it is proven here that such a dependence must necessarily have the form $Φ({ξ_α})=-ξ_0\ln(1-ξ_3)+Ψ(y)ξ_1ξ_2/(1-ξ_3)$, where $y\equiv {ξ_2^2}/{12πξ_1 (1-ξ_3)}$ is a scaled variable and $Ψ(y)$ is an arbitrary dimensionless scaling function which can be determined from the free-energy density of the one-component system. Extension to the inhomogeneous case is achieved by standard replacements of the variables ${ξ_α}$ by the fundamental-measure (scalar, vector, and tensor) weighted densities ${n_α(\mathbf{r})}$. Comparison with computer simulations shows the superiority of this bulk free energy over the White Bear one.

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