School of Physics and Electronics, Central South University, Changsha, Hunan 410083, China.
J Chem Phys. 2013 Jun 28;138(24):244115. doi: 10.1063/1.4811285.
The first four perturbation coefficients in the expansion of the Helmholtz free energy in power series of the inverse of the reduced temperature for a number of potential models with hard-sphere cores plus core-softened and discontinuous tails are obtained from Monte Carlo simulations. The potential models considered include square-well, double square-well, and square-shoulder plus square-well, with different potential parameters. These simulation data are used to evaluate the performance of a traditional macroscopic compressibility approximation (MCA) for the second order coefficient and a recent coupling parameter series expansion (CPSE) for the first four coefficients. Comprehensive comparison indicates the incapability of the MCA for the second order coefficient in most non-stringent situations, and significance of the CPSE in accurately calculating these four coefficients.
从蒙特卡罗模拟中获得了一些具有硬球核外加核软化和不连续尾部的势能模型在温度倒数的幂级数展开式中亥姆霍兹自由能的前四个微扰系数。所考虑的势能模型包括方阱、双方阱和方肩加方阱，具有不同的势能参数。这些模拟数据用于评估传统的宏观压缩性近似（MCA）对二阶系数和最近的耦合参数级数展开（CPSE）对前四个系数的性能。综合比较表明，MCA 对于大多数非严格情况的二阶系数都不适用，而 CPSE 在准确计算这四个系数方面具有重要意义。
