The classical Density functional theory (DFT) has become a powerful tool to describe the microscopic structure of fluids as the radial distribution function. One of its particular capabilities is to express the thermodynamic properties of those fluids even under the influence of external potentials, such as fluid-solid interaction. However, good models for the Helmholtz free-energy functionals are necessary to improve the results. In this work, we present a self-consistent thermodynamic perturbation theory for the excess Helmholtz free-energy from the DFT applied to hard-core fluids. The new perturbation theory is solved self-consistently without any closure relation to solving the Ornstein-Zernike equation explicitly. We compare the performance of our self-consistent perturbation theory with the results obtained with the well-known second-order Barker-Henderson perturbation theory for the hard-core Yukawa and square-well fluids. Moreover, we propose two versions of the DFT to describe the perturbative contribution: one based on the weighted density approximation theory and another from a modified mean-field theory. The present results confirm the modified mean-field theory as a better option to calculate the thermodynamic and structural properties of hard-core fluids.

经典的密度泛函理论 (DFT) 已成为将流体微观结构描述为径向分布函数的有力工具。它的一项特殊功能是即使在外部电位（例如流固相互作用）的影响下也能表达这些流体的热力学特性。然而，亥姆霍兹自由能泛函的良好模型对于改进结果是必要的。在这项工作中，我们针对应用于硬核流体的 DFT 的过量亥姆霍兹自由能提出了自洽热力学扰动理论。新微扰理论自洽求解，与明确求解 Ornstein-Zernike 方程没有任何闭合关系。我们将自洽扰动理论的性能与著名的二阶 Barker-Henderson 扰动理论对硬核 Yukawa 和方井流体的结果进行了比较。此外，我们提出了两个版本的 DFT 来描述微扰贡献：一个基于加权密度近似理论，另一个来自修改后的平均场理论。目前的结果证实，修正平均场理论是计算硬核流体热力学和结构特性的更好选择。