Short-chain alcohols at high dilution are among the very few solutes that enhance the anomalous behavior of water, in particular the value of the temperature of maximum density. This peculiar feature, first discovered experimentally in the early twenties, has remained elusive to a full explanation in terms of atomistic models. In this paper, we first introduce a two-site model of tert-butanol in which the interactions involving hydrogen bonding are represented by a Stillinger–Weber potential, following the ideas established by Molinero and Moore (2009) for water. Our model parameters are fit so as to semi-quantitatively reproduce the experimental densities and vaporization enthalpies of previously proposed united atom and all atom OPLS models. Water is represented using the aforementioned potential model introduced by Molinero and Moore, with cross interaction parameters between water and tert-butanol optimized to yield a reasonable description of the experimental excess enthalpies and volumes over the whole composition range of the mixture. We will see that our simple model is able to reproduce the presence of a maximum in the change of the temperature of maximum density for very low alcohol mole fractions, followed by a considerable decrease until the density anomaly itself disappears. We have correlated this behavior with changes in the local structure of water and compared it with the results of all-atom simulations of water/tert-butanol mixtures.

高度稀释的短链醇是极少数能增强水异常行为，尤其是最大密度温度值的溶质之一。这种奇特的特征最初是在 20 年代初通过实验发现的，至今仍难以用原子模型进行全面解释。在本文中，我们首先介绍了一个叔丁醇的双位点模型，其中涉及氢键的相互作用由 Stillinger-Weber 势表示，遵循 Molinero 和 Moore (2009) 为水建立的想法。我们的模型参数适合半定量重现先前提出的联合原子和所有原子 OPLS 模型的实验密度和汽化焓。使用 Molinero 和 Moore 引入的上述潜在模型表示水，优化水和叔丁醇之间的交叉相互作用参数，以合理描述混合物整个组成范围内的实验过量焓和体积。我们将看到，我们的简单模型能够再现极低醇摩尔分数的最大密度温度变化的最大值，然后显着降低，直到密度异常本身消失。我们将这种行为与水局部结构的变化相关联，并将其与水/叔丁醇混合物的全原子模拟结果进行了比较。我们将看到，我们的简单模型能够再现极低醇摩尔分数的最大密度温度变化的最大值，然后显着降低，直到密度异常本身消失。我们将这种行为与水局部结构的变化相关联，并将其与水/叔丁醇混合物的全原子模拟结果进行了比较。我们将看到，我们的简单模型能够再现极低醇摩尔分数的最大密度温度变化的最大值，然后显着降低，直到密度异常本身消失。我们将这种行为与水局部结构的变化相关联，并将其与水/叔丁醇混合物的全原子模拟结果进行了比较。