连续肩井势异常的软依赖性
Softness dependence of the Anomalies for the Continuous Shouldered Well potential
摘要：
通过分子动力学模拟，我们研究了一个质点系通过一个连续的各向同性的成对核软化势相互作用的粒子系统，该势由一个排斥肩和一个吸引阱组成。该模型显示了一个相图与三个流体相，气-液临界点，液-液临界点，密度，扩散和结构的异常。异常的层次与水的层次相同。我们研究了势的软度变化对异常的影响。我们发现，随着软核的变陡，密度异常区和扩散异常区在T - ρ平面上收缩，而构造异常区受影响较小。因此，液体可以具有不具有密度或扩散异常的异常结构行为。我们表明，通过考虑作为有效距离对应于高密度液体中的径向分布函数g（r）的前两个峰值的最大值，我们可以推广到连续的双尺度电位的密度和扩散的异常发生的标准，最初提出的不连续的电位。我们观察到，知识的前两个协调壳层的液体内的结构行为是不够的，以建立异常的发生。通过引入过量熵的累积序积分的密度导数，我们表明，在第四配位壳层的距离大的结构顺序调节的反常行为。通过比较不同的软势的结果，我们得出结论，密度和扩散异常的消失陡峭的电位是由于一个更结构化的短程秩序。所有这些结果增加了我们的理解，如何知道的相互作用势，我们可以评估可能存在的异常的液体。
英文摘要：
By molecular dynamic simulations we study a system of particles interacting through a continuous isotropic pairwise core-softened potential consisting of a repulsive shoulder and an attractive well. The model displays a phase diagram with three fluid phases, a gas-liquid critical point, a liquid-liquid critical point, and anomalies in density, diffusion and structure. The hierarchy of the anomalies is the same as for water. We study the effect on the anomalies of varying the softness of the potential. We find that, making the soft-core steeper, the regions of density and diffusion anomalies contract in the T - ρ plane, while the region of structural anomaly is weakly affected. Therefore, a liquid can have anomalous structural behavior without density or diffusion anomalies. We show that, by considering as effective distances those corresponding to the maxima of the first two peaks of the radial distribution function g(r) in the high-density liquid, we can generalize to continuous two-scales potentials a criterion for the occurrence of the anomalies of density and diffusion, originally proposed for discontinuous potentials. We observe that the knowledge of the structural behavior within the first two coordination shells of the liquid is not enough to establish the occurrence of the anomalies. By introducing the density derivative of the the cumulative order integral of the excess entropy we show that the anomalous behavior is regulated by the structural order at distances as large as the fourth coordination shell. By comparing the results for different softness of the potential, we conclude that the disappearing of the density and diffusion anomalies for the steeper potentials is due to a more structured short-range order. All these results increase our understanding on how, knowing the interaction potential, we can evaluate the possible presence of anomalies for a liquid.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
