Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva c. 5, SI-1000 Ljubljana, Slovenia.
J Chem Phys. 2012 Dec 28;137(24):244502. doi: 10.1063/1.4772582.
The canonical Monte Carlo computer simulations and integral equation theory were applied to examine the structural and thermodynamic properties of a mixture of ions and a core-softened fluid molecules. The positive and negative ions forming a +1:-1 salt were modeled as charged hard spheres, immersed in the dielectric medium. It was shown previously that the core-softened fluid under study is characterized by a set of structural, thermodynamic, and dynamic anomalies. The principal objective of this work was to elucidate how the presence of ions alters this behavior. The structural properties of the mixtures are discussed in terms of the pair distribution functions; in addition, the pair contribution to the excess entropy was calculated. Thermodynamic properties are investigated by using the dependencies of energy and compressibility factor on density, composition of the mixture, and reduced temperature. The heat capacity was also evaluated. Our principal findings concern the description of structural anomalies in the mixture, the dependence of the temperature of maximum density on the ionic concentration, and establishing the regions delimiting the structural and thermodynamic anomalies of the model mixture.
本研究采用正则蒙特卡罗计算机模拟和积分方程理论，考察了离子和核软化流体分子混合物的结构和热力学性质。形成+1：-1 盐的正、负离子被建模为带电硬球体，沉浸在介电介质中。之前已经表明，所研究的核软化流体具有一系列结构、热力学和动力学异常。这项工作的主要目的是阐明离子的存在如何改变这种行为。通过对配分函数的讨论来研究混合物的结构特性；此外，还计算了对超额熵的对贡献。通过使用能量和压缩因子对密度、混合物组成和还原温度的依赖性来研究热力学性质。还评估了热容。我们的主要发现涉及混合物中结构异常的描述、最大密度温度对离子浓度的依赖性以及确定模型混合物结构和热力学异常的区域。
